@article{altaqui_schrickx_sen_li_rech_lee_balar_you_kim_escuti_et al._2021, title={Bio-inspired spectropolarimetric sensor based on tandem organic photodetectors and multi-twist liquid crystals}, volume={29}, ISSN={["1094-4087"]}, url={https://doi.org/10.1364/OE.431858}, DOI={10.1364/OE.431858}, abstractNote={Simultaneous spectral and polarimetric imaging enables versatile detection and multimodal characterization of targets of interest. Current architectures incorporate a 2×2 pixel arrangement to acquire the full linear polarimetric information causing spatial sampling artifacts. Additionally, they suffer from limited spectral selectivity and high color crosstalk. Here, we demonstrate a bio-inspired spectral and polarization sensor structure based on integrating semitransparent polarization-sensitive organic photovoltaics (P-OPVs) and liquid crystal polymer (LCP) retarders in a tandem configuration. Color tuning is realized by leveraging the dynamic chromatic retardation control of LCP films, while polarization sensitivity is realized by exploiting the flexible anisotropic properties of P-OPVs. The structure is marked by its ultra-thin design and its ability to detect spectral and polarimetric contents along the same optical axis, thereby overcoming the inherent limitations associated with conventional division-of-focal plane sensors.}, number={26}, journal={OPTICS EXPRESS}, publisher={The Optical Society}, author={Altaqui, Ali and Schrickx, Harry and Sen, Pratik and Li, Lingshan and Rech, Jeromy and Lee, Jin-Woo and Balar, Nrup and You, Wei and Kim, Bumjoon J. and Escuti, Michael and et al.}, year={2021}, month={Dec}, pages={43953–43969} }
 @article{altaqui_sen_schrickx_rech_lee_escuti_you_kim_kolbas_brendan t. o'connor_et al._2021, title={Mantis shrimp-inspired organic photodetector for simultaneous hyperspectral and polarimetric imaging}, volume={7}, ISSN={["2375-2548"]}, url={https://doi.org/10.1126/sciadv.abe3196}, DOI={10.1126/sciadv.abe3196}, abstractNote={Semitransparent polarization-sensitive organic detectors reveal unprecedented degrees of freedom for multidimensional imaging.}, number={10}, journal={SCIENCE ADVANCES}, publisher={American Association for the Advancement of Science (AAAS)}, author={Altaqui, Ali and Sen, Pratik and Schrickx, Harry and Rech, Jeromy and Lee, Jin-Woo and Escuti, Michael and You, Wei and Kim, Bumjoon J. and Kolbas, Robert and Brendan T. O'Connor and et al.}, year={2021}, month={Mar} }
 @article{altaqui_kolbas_escuti_brendan t. o'connor_kudenov_2021, title={Organic-based photodetectors for multiband spectral imaging}, volume={60}, ISSN={["2155-3165"]}, DOI={10.1364/AO.417069}, abstractNote={Using organic photodetectors for multispectral sensing is attractive due to their unique capabilities to tune spectral response, transmittance, and polarization sensitivity. Existing methods lack tandem multicolor detection and exhibit high spectral cross talk. We exploit the polarization sensitivity of organic photodetectors, together with birefringent optical filters to design single-pixel multispectral detectors that achieve high spectral selectivity and good radiometric performance. Two different architectures are explored and optimized, including the Solc-based and multitwist-retarder-based organic photodetectors. Although the former demonstrated a higher spectral resolution, the latter enables a more compact sensor as well as greater flexibility in device fabrication.}, number={8}, journal={APPLIED OPTICS}, author={Altaqui, Ali and Kolbas, Robert M. and Escuti, Michael J. and Brendan T. O'Connor and Kudenov, Michael W.}, year={2021}, month={Mar}, pages={2314–2323} }
 @article{mishra_mattingly_kolbas_2019, title={Application of deconvolution to recover frequency-domain multiplexed detector pulses}, volume={929}, ISSN={["1872-9576"]}, DOI={10.1016/j.nima.2019.03.043}, abstractNote={Multiplexing of radiation detectors reduces the number of readout channels, which in turn reduces the number of digitizer input channels for data acquisition.We recently demonstrated frequency domain multiplexing (FDM) of pulse mode radiation detectors using a resonator that converts the detector signal into a damped sinusoid by convolution.The detectors were given unique "tags" by the oscillation frequency of each resonator.The charge collected and the timeof-arrival of the detector pulse were estimated from the corresponding resonator output in the frequency domain.In this paper, we demonstrate a new method to recover the detector pulse from the damped sinusoidal output by deconvolution.Deconvolution converts the frequency-encoded detector signal back to the original detector pulse.We have developed a new prototype FDM system to multiplex organic scintillators based on convolution and deconvolution.Using the new prototype, the charge collected under the anode pulse can be estimated from the recovered pulse with an uncertainty of about 4.4 keVee (keV electron equivalent).The time-of-arrival can be estimated from the recovered pulse with an uncertainty of about 102 ps.We also used a CeBr 3 inorganic scintillator to measure the Cs-137 gamma spectrum using the recovered pulses and found a standard deviation of 13.8 keV at 662 keV compared to a standard deviation of 13.5 keV when the original pulses}, journal={NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT}, author={Mishra, M. and Mattingly, J. and Kolbas, R. M.}, year={2019}, month={Jun}, pages={57–65} }
 @article{mishra_mattingly_mueller_kolbas_2018, title={Frequency domain multiplexing of pulse mode radiation detectors}, volume={902}, ISSN={["1872-9576"]}, DOI={10.1016/j.nima.2018.06.023}, abstractNote={Abstract The capability to multiplex scintillation detectors or other pulse mode radiation detectors is necessary in some applications where a large number of detectors is required. Frequency domain multiplexing has been previously implemented for applications in astronomy using amplitude modulation on radiation detectors such as transition-edge sensors. We propose an alternative method for multiplexing pulse mode radiation detectors in the frequency domain using convolution. We pass the detector signal to a resonator circuit that converts a detector pulse to a damped sinusoid of a specific frequency which gives a unique tag to the detector. We have developed a prototype frequency-domain multiplexed system for four EJ-309 organic scintillator detectors using four resonators of unique frequencies. The resonator outputs are combined using a fan-in circuit which is then connected to a single digitizer input. Using this system, we demonstrate that the charge collected under the original anode pulse can be estimated from the power spectrum of the damped sinusoid with a relative uncertainty of about 2%. The time-of-arrival of the anode pulse can be estimated using constant fraction discrimination applied to the leading edge of the damped sinusoid with an uncertainty of about 450 ps. We also used a CeBr 3 detector to test the performance of our system for spectroscopic applications and found only small degradation in the resolution for a multiplexed detector.}, journal={NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT}, author={Mishra, M. and Mattingly, J. and Mueller, J. M. and Kolbas, R. M.}, year={2018}, month={Sep}, pages={117–122} }
 @article{al-ajmi_kolbas_roberts_rajagopal_cook_piner_linthicum_2008, title={Stimulated emission and lasing from an Al0.13Ga0.87N∕GaN double heterostructure grown on a silicon substrate}, volume={92}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.2819614}, DOI={10.1063/1.2819614}, abstractNote={Stimulated emission and laser action with well developed longitudinal optical modes from an Al0.13Ga0.87N∕GaN double heterostructure with a 25nm GaN active layer grown on a silicon substrate by metal-organic chemical vapor deposition is demonstrated. Lasing was observed from cleaved platelets at room temperature with well resolved Fabry-Pérot modes at a wavelength as short as 368nm at room temperature. A clear threshold was observed in the plot of the emission intensity versus the pumping power at both 77K and room temperature. The effective index of refraction during laser operation was measured to be 2.65.}, number={2}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Al-Ajmi, F. S. and Kolbas, R. M. and Roberts, J. C. and Rajagopal, P. and Cook, J. W., Jr. and Piner, E. L. and Linthicum, K. J.}, year={2008}, month={Jan}, pages={021118} }
 @article{al-ajmi_kolbas_roberts_rajagopal_cook_piner_linthicum_2007, title={Room temperature laser action from multiple bands in photoexcited GaN grown on a silicon substrate}, volume={90}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.2722201}, DOI={10.1063/1.2722201}, abstractNote={Room temperature stimulated emission and laser action with well developed longitudinal optical modes from high-quality GaN films grown on silicon substrates by metal-organic chemical-vapor deposition are presented. Laser action with well developed Fabry-Pérot modes involving the A, B, and C bands was observed. Stimulated emission one exciton below the A band and the B band and one longitudinal optical phonon below the B band was also observed. The effective index of refraction during laser operation was measured to be 2.9.}, number={15}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Al-Ajmi, F. S. and Kolbas, R. M. and Roberts, J. C. and Rajagopal, P. and Cook, J. W., Jr. and Piner, E. L. and Linthicum, K. J.}, year={2007}, month={Apr}, pages={151116} }
 @article{chang_kolbas_reitmeier_davis_2006, title={Effect of thermal annealing on the metastable optical properties of GaN thin films}, volume={24}, ISSN={["0734-2101"]}, DOI={10.1116/1.2209656}, abstractNote={The optical metastability in unintentionally doped GaN (0001) films grown on AlN∕SiC substrates has been investigated as a function of thermal annealing conditions using photoluminescence and optical microscopy. Annealing at 800°C for 48h in 1atm of flowing nitrogen produced no change in the metastability. Annealing at 800°C in ultrahigh vacuum for 48h eliminated the phenomenon. Exposure of the sample to ultraviolet light during the latter anneal reduced the time to eliminate the metastability. This phenomenon was restored by subsequently annealing in ammonia at 775°C for 3h. These results suggest that the presence and elimination of the optical metastability are related to the presence in and the elimination of hydrogen from the GaN.}, number={4}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Chang, Y. C. and Kolbas, R. M. and Reitmeier, Z. J. and Davis, R. F.}, year={2006}, pages={1051–1054} }
 @article{chang_cai_muth_kolbas_park_cuomo_hanser_bumgarner_2003, title={Optical and structural studies of hydride vapor phase epitaxy grown GaN}, volume={21}, ISSN={["0734-2101"]}, DOI={10.1116/1.1568346}, abstractNote={Thick films of hydride vapor phase epitaxy (HVPE) grown GaN were studied by various techniques. Time-integrated and time-resolved photoluminescence (PL) measurements were performed at room temperature and 77 K. The time-integrated PL spectrum has no observed deep-level transitions and a very narrow linewidth, which indicates good material quality. Time-resolved PL spectra are also presented and the temporal evolution of the PL around the band-gap exhibits a biexponential decay with a fast and a slow decay component. Cathodoluminescence, x-ray, and Raman spectroscopy were also used. The full width half maximum of the x-ray rocking curve for our sample is approximately 375 arcsec. The polarized Raman spectra exhibited only the allowed modes. The deposited GaN films were found to be relatively stress free. The x ray and Raman analysis also revealed that the HVPE-grown GaN films are of high crystal quality. The effect of thermal annealing on the sample was also investigated by time-integrated and time-resolved PL and Raman spectroscopy. No significant changes in the material were observed in either time-integrated or Raman spectroscopy. The film was thermally stable upon annealing up to 1000 °C in N2 ambient based on the results of these measurements. In time-resolve photoluminescence measurement, the temporal evolution of the band-edge transitions broadens after each annealing step and is significantly different after the 1000 °C anneal.}, number={3}, journal={JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A}, author={Chang, YC and Cai, AL and Muth, JF and Kolbas, RM and Park, M and Cuomo, JJ and Hanser, A and Bumgarner, J}, year={2003}, pages={701–705} }
 @article{chang_cai_johnson_muth_kolbas_reitmeier_einfeldt_davis_2002, title={Electron-beam-induced optical memory effects in GaN}, volume={80}, ISSN={["0003-6951"]}, DOI={10.1063/1.1469222}, abstractNote={Metastable effects in unintentionally doped GaN films grown on SiC substrates have been investigated using cathodoluminescence (CL). Memory effect patterns produced optically are observed in CL images. An electron beam can also produce memory effect patterns and the resulting changes in the luminescence spectra are quite similar for either optical or electron-beam-induced patterns. CL spectra reveal that the yellow luminescence at 2.2 eV increases significantly with little change in the band-edge emission in both cases. Samples that do not exhibit optically induced memory effects are also investigated and do not exhibit electron-beam-induced patterns, either. Monochromatic CL images at 540 and 365 nm confirm the similarity of optically and electron-beam-induced memory effects based on changes in luminescence spectra.}, number={15}, journal={APPLIED PHYSICS LETTERS}, author={Chang, YC and Cai, AL and Johnson, MAL and Muth, JF and Kolbas, RM and Reitmeier, ZJ and Einfeldt, S and Davis, RF}, year={2002}, month={Apr}, pages={2675–2677} }
 @article{kou_hall_strohhofer_polman_zhang_kolbas_heller_dupuis_2002, title={Er-doped AlGaAs native oxides: Photoluminescence characterization and process optimization}, volume={8}, ISSN={["1077-260X"]}, DOI={10.1109/JSTQE.2002.801689}, abstractNote={We present 300 K photoluminescence (PL) characterization data for wet thermal native oxides of Al/sub 0.58/Ga/sub 0.42/As films grown by metal organic chemical vapor deposition and doped with Er via multiple high-energy ion implants (for 0.0675, 0.135, and 0.27 atomic percent (at.%) peak Er concentrations), and Al/sub 0.5/Ga/sub 0.5/As and Al/sub 0.8/In/sub 0.2/As films doped with Er (0.03-0.26 at.%) during molecular beam epitaxy crystal growth. Broad spectra with a /spl sim/50-nm full-width at half-maximum and a PL peak at 1.534 /spl mu/m are observed, characteristic of Al/sub 2/O/sub 3/:Er films. The dependencies of PL intensity, spectra, and lifetime on annealing temperature (675/spl deg/C-900/spl deg/C), time (2-60 min) and As overpressure (0-0.82 atm) are studied to optimize the annealing process, with As considered as a possible quenching mechanism. Wet and dry-oxidized films are compared to explore the role of hydroxyl (OH) groups identified by Fourier transform infrared (FTIR) spectroscopy. FTIR experiments employing heavy water (D/sub 2/O) suggest that OH groups in wet oxidized AlGaAs come mainly from post-oxidation adsorption of atmospheric moisture. AlGaAs:Er films wet oxidized with 0.1% O/sub 2/ added to the N/sub 2/ carrier gas show a fourfold PL intensity increase, doubled PL lifetime to /spl tau//spl sim/5.0 ms (0.27 at.% implanted sample), and the lowest degree of concentration quenching.}, number={4}, journal={IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS}, author={Kou, LG and Hall, DC and Strohhofer, C and Polman, A and Zhang, T and Kolbas, RM and Heller, RD and Dupuis, RD}, year={2002}, pages={880–890} }
 @article{park_maria_cuomo_chang_muth_kolbas_nemanich_carlson_bumgarner_2002, title={X-ray and Raman analyses of GaN produced by ultrahigh-rate magnetron sputter epitaxy}, volume={81}, ISSN={["0003-6951"]}, DOI={10.1063/1.1506781}, abstractNote={Thick films of GaN were studied by x-ray diffraction and Raman spectroscopy. The GaN thick films were deposited on (0001) sapphire using ultrahigh-rate magnetron sputter epitaxy with typical growth rates as high as 10–60 μm/min. The width of the x-ray rocking curve from the (0002) reflection for the sample produced by this technique is ∼300 arcsec, which is unprecedented for GaN produced by a sputtering-type process. Our recent sample shows an x-ray rocking curve width of 240 arcsec. Only allowed modes were observed in the polarized Raman spectra. The background free carrier concentration is lower than 3×1016 cm−3. The phonon lifetime of the Raman E2(2) mode of the sputtered GaN was comparable to that of bulk single crystal GaN grown by sublimation. The quality of the film was uniform across the wafer. The film was thermally stable upon annealing in N2 ambient. The x-ray and Raman analyses revealed that the sputtered GaN films are of high crystalline quality.}, number={10}, journal={APPLIED PHYSICS LETTERS}, author={Park, M and Maria, JP and Cuomo, JJ and Chang, YC and Muth, JF and Kolbas, RM and Nemanich, RJ and Carlson, E and Bumgarner, J}, year={2002}, month={Sep}, pages={1797–1799} }
 @article{park_teng_sakhrani_mclaurin_kolbas_sanwald_nemanich_hren_cuomo_2001, title={Optical characterization of wide band gap amorphous semiconductors (a-Si : C : H): Effect of hydrogen dilution}, volume={89}, ISSN={["1089-7550"]}, DOI={10.1063/1.1332421}, abstractNote={The effect of hydrogen dilution on the optical properties of a wide band gap amorphous semiconductor (a-Si:C:H) was investigated. The samples were prepared by glow discharge decomposition of tetramethylsilane and were characterized primarily by optical techniques: spectroscopic ellipsometry, Raman scattering, infrared absorption, spectrophotometry, and UV photoluminescence. The deposition rate decreased with hydrogen dilution, while the silicon to carbon ratio remained constant with the addition of hydrogen. The optical band gap of this material increased as the hydrogen flow rate increased. Infrared absorption studies show that the concentration of hydrogen which is bonded to carbon decreases systematically upon hydrogen dilution. Hydrogen dilution appears to reduce the size and concentration of sp2 bonded carbon clusters, possibly caused by the etching of sp2 clusters by atomic hydrogen. The result was also supported by the shift of the Raman G peak position to a lower wave number region. Room temperature photoluminescence in the visible spectrum was observed with UV excitation.}, number={2}, journal={JOURNAL OF APPLIED PHYSICS}, author={Park, M and Teng, CW and Sakhrani, V and McLaurin, MB and Kolbas, RM and Sanwald, RC and Nemanich, RJ and Hren, JJ and Cuomo, JJ}, year={2001}, month={Jan}, pages={1130–1137} }
 @article{chang_oberhofer_muth_kolbas_davis_2001, title={Optical metastability of subband gap (2.2 eV) yellow luminescence in GaN}, volume={79}, ISSN={["0003-6951"]}, DOI={10.1063/1.1381417}, abstractNote={Optical metastability has been studied in undoped GaN films grown on SiC substrates having a previously deposited AlN buffer layer. Brief exposures to a higher intensity ultraviolet light resulted in temporary changes in the optical properties of the GaN layer. The photoinduced changes created high contrast patterns on samples that could be observed under an optical microscope with lower intensity ultraviolet excitation. The subband gap yellow photoluminescence peak at 2.2 eV increased significantly after the patterns were created. This change slowly returned (hours) to its initial value at room temperature. The retention time decreased to a few seconds at temperatures above 100 °C. The data showed that a 1.34 eV thermal activation energy exists, which suggests that the cause of these metastable properties is related to the subband gap yellow luminescence.}, number={3}, journal={APPLIED PHYSICS LETTERS}, author={Chang, YC and Oberhofer, AE and Muth, JF and Kolbas, RM and Davis, RF}, year={2001}, month={Jul}, pages={281–283} }
 @article{teng_aboelfotoh_davis_muth_kolbas_2001, title={Photoluminescence and electrical characteristics of the two-dimensional electron gas in Si delta-doped GaN layers}, volume={78}, ISSN={["1077-3118"]}, DOI={10.1063/1.1353836}, abstractNote={We have studied the electrical and photoluminescence (PL) properties of a Si delta-doped GaN layer grown by metalorganic chemical vapor deposition. The Hall mobility and electron sheet concentration are 726 cm2/V s and 1.9×1012 cm−2, respectively, at 2 K. A PL peak located at 78 meV below the band gap of GaN is observed at 77 K. This PL peak is attributed to the radiative recombination between electrons in the two-dimensional quantum states and photoexcited holes in GaN, which is consistent with simulation results using a one-dimensional Poisson and Schrödinger equation solver. The peak disappears at temperatures higher than 77 K and is not observed in uniformly doped GaN layers.}, number={12}, journal={APPLIED PHYSICS LETTERS}, author={Teng, CW and Aboelfotoh, MO and Davis, RF and Muth, JF and Kolbas, RM}, year={2001}, month={Mar}, pages={1688–1690} }
 @article{balkas_sitar_bergman_shmagin_muth_kolbas_nemanich_davis_2000, title={Growth and characterization of GaN single crystals}, volume={208}, ISSN={["0022-0248"]}, DOI={10.1016/S0022-0248(99)00445-5}, abstractNote={Up to 3 mm long GaN single crystals were grown by sublimation of cold pressed GaN pellets or evaporation of gallium (Ga) metal under an ammonia (NH3) flow in a dual heater, high-temperature growth system. A growth rate of 500 μm/h along the [0 0 0 1] direction was achieved using a source temperature of 1200°C, a total pressure of 760 Torr, and an NH3 flow rate of 50 sccm. The resulting crystals were transparent, possessed low aspect ratios and well-defined growth facets. The only impurity present at high concentrations was oxygen (3×1018 atoms/cm3). Photoluminescence studies conducted at 77 K showed a sharp emission peak centered at 359 nm. Time-dependent photoluminescence measurements revealed optical metastability in bulk GaN. Raman spectroscopy yielded narrow peaks representing only the modes allowed for the wurtzite structure. All characterization studies confirmed excellent crystalline and optical quality of the obtained single crystals.}, number={1-4}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Balkas, CM and Sitar, Z and Bergman, L and Shmagin, IK and Muth, JF and Kolbas, R and Nemanich, RJ and Davis, RF}, year={2000}, month={Jan}, pages={100–106} }
 @article{teng_muth_kolbas_hassan_sharma_kvit_narayan_2000, title={Quantum confinement of E-1 and E-2 transitions in Ge quantum dots embedded in an Al2O3 or an AlN matrix}, volume={76}, ISSN={["0003-6951"]}, DOI={10.1063/1.125650}, abstractNote={Alternating layers of Ge quantum dots embedded in either Al2O3 or AlN matrices were deposited on sapphire substrates by pulsed-laser deposition. The characteristics of the dots are shown to be independent of the surrounding matrix. The dots size (73, 130, 160, and 260 ű5%) was controlled by the laser energy density and deposition time, and was characterized by high-resolution transmission electron microscopy. The dots were single crystalline with no apparent GeOx interfacial layers. Transmission spectroscopy at room temperature and 77 K was used to probe the above-band-edge absorption of the Ge nanodots. The spectral positions of both E1/E1+Δ1 and E2 transitions were found to shift to higher energy in the absorption spectra with decreasing nanodot sizes. This indicates that strong quantum-confinement effect permits the optical properties of Ge dots to be modified in a controlled manner.}, number={1}, journal={APPLIED PHYSICS LETTERS}, author={Teng, CW and Muth, JF and Kolbas, RM and Hassan, KM and Sharma, AK and Kvit, A and Narayan, J}, year={2000}, month={Jan}, pages={43–45} }
 @inproceedings{teng_muth_kolbas_hassan_sharma_narayan_2000, title={Quantum confinement of E1 and E2 transitions in Ge quantum dots embedded in Al203 or an AlN matrix}, booktitle={Optical microstructural characterization of semiconductors  (Materials Research Society proceedings, vol. 588)}, publisher={Pittsburgh, Pa.: Materials Research Society}, author={Teng, C. W. and Muth, J. F. and Kolbas, R. M. and Hassan, K. M. and Sharma, A. K. and Narayan, J.}, editor={J. Piqueras, T. Sekiguchi and Unlu, M. S.Editors}, year={2000} }
 @inproceedings{hassan_sharma_narayan_muth_teng_kolbas_2000, title={Size effect in germanium nanostructures fabricated by pulsed laser deposition}, booktitle={Nanophase and Nanocomposite Materials III  (Materials Research Society proceedings; vol. 581)}, publisher={Pittsburgh, Pa.: Materials Research Society}, author={Hassan, K. M. and Sharma, A. K. and Narayan, J. and Muth, J. F. and Teng, C. W. and Kolbas, R. M.}, editor={H. Hahn, S. Komarneni and Parker, J. C.Editors}, year={2000} }
 @inproceedings{sharma_jin_narayan_teng_muth_kolbas_holland_2000, title={Structural and optical property investigations on Mg-Alloying in epitaxial zinc oxide films on sapphire}, number={2000}, booktitle={MRS Internet Journal of Nitride Semiconductor Research}, author={Sharma, A. K. and Jin, C. and Narayan, J. and Teng, C. W. and Muth, J. F. and Kolbas, R. M. and Holland, O. W.}, year={2000} }
 @article{muth_brown_johnson_yu_kolbas_cook_schetzina_1999, title={Absorption coefficient and refractive index of GaN, AlN and AlGaN alloys}, volume={4S1}, number={G5.2}, journal={MRS Internet Journal of Nitride Semiconductor Research}, author={Muth, J. F. and Brown, J. D. and Johnson, M. A. L. and Yu, Z. H. and Kolbas, R. M. and Cook, J. W. and Schetzina, J. F.}, year={1999} }
 @article{joshkin_parker_bedair_muth_shmagin_kolbas_piner_molnar_1999, title={Effect of growth temperature on point defect density of unintentionally doped GaN grown by metalorganic chemical vapor deposition and hydride vapor phase epitaxy}, volume={86}, ISSN={["0021-8979"]}, DOI={10.1063/1.370727}, abstractNote={We report on the investigation of the effect of growth temperature on point defect density of unintentionally doped GaN grown by atmospheric pressure metalorganic chemical vapor deposition and hydride vapor phase epitaxy. A correlation between photoluminescence (PL) spectra and the concentration of donors and acceptors in unintentionally doped GaN is presented. The effects of oxygen and native acceptors on the electrical and optical properties of GaN epitaxial layers are discussed and a classification of PL data is presented. On this basis we show that oxygen creates a shallow donor in GaN with an activation energy of about 23.5±1 meV. We determine that the concentration of native acceptors in GaN increases with an increase in growth temperature. These native acceptors, probably gallium antisites (GaN) and/or gallium vacancies (VGa), are nonradiative defects. We show that a second donor level in GaN has an activation energy of about 52.5±2.5 meV and produces a PL peak with an energy of about 3.45 eV at low temperatures. From Hall investigations we show that a third donor in GaN has an activation energy of 110±10 meV.}, number={1}, journal={JOURNAL OF APPLIED PHYSICS}, author={Joshkin, VA and Parker, CA and Bedair, SM and Muth, JF and Shmagin, IK and Kolbas, RM and Piner, EL and Molnar, RJ}, year={1999}, month={Jul}, pages={281–288} }
 @article{muth_kolbas_sharma_oktyabrsky_narayan_1999, title={Excitonic structure and absorption coefficient measurements of ZnO single crystal epitaxial films deposited by pulsed laser deposition}, volume={85}, ISSN={["1089-7550"]}, DOI={10.1063/1.370601}, abstractNote={The optical properties of high quality single crystal epitaxial zinc oxide thin films grown by pulsed laser deposition on c-plane sapphire substrates were studied. It was found that annealing the films in oxygen dramatically improved the optical and electrical properties. The absorption coefficient, band gap, and exciton binding energies were determined by transmission measurements and photoluminescence. In both the annealed and the as-deposited films excitonic absorption features were observed at both room temperature and 77 K. In the annealed films the excitonic absorption peaks were substantially sharper and deep level photoluminescence was suppressed.}, number={11}, journal={JOURNAL OF APPLIED PHYSICS}, author={Muth, JF and Kolbas, RM and Sharma, AK and Oktyabrsky, S and Narayan, J}, year={1999}, month={Jun}, pages={7884–7887} }
 @article{bergmann_ozgur_casey_muth_chang_kolbas_rao_eom_schurman_1999, title={Linear optical properties of a heavily Mg-doped Al0.09Ga0.91N epitaxial layer}, volume={74}, ISSN={["0003-6951"]}, DOI={10.1063/1.124102}, abstractNote={The room-temperature absorption coefficient and ordinary refractive index for a ∼0.4-μm-thick p-type wurtzite Al0.09Ga0.91N epitaxial layer were determined via optical transmission measurements. The layer was grown by metal organic chemical vapor deposition and heavily doped (∼5×1019 cm−3) with Mg. Additional measurements of the refractive index by prism coupling to the layer confirmed the transmission results. The low-temperature AlN buffer layer altered the expected interference fringes of the transmission spectrum below the band-gap energy and had to be accounted for in the analysis. The absorption coefficient exhibited band-tail effects and had a reduced slope near band-gap energy as compared to undoped GaN. Using a detailed balance argument, the reduced slope was consistent with the lack of a peak in the continuous-wave photoluminescent emission.}, number={21}, journal={APPLIED PHYSICS LETTERS}, author={Bergmann, MJ and Ozgur, U and Casey, HC and Muth, JF and Chang, YC and Kolbas, RM and Rao, RA and Eom, CB and Schurman, M}, year={1999}, month={May}, pages={3188–3190} }
 @article{sharma_narayan_muth_teng_jin_kvit_kolbas_holland_1999, title={Optical and structural properties of epitaxial MgxZn1-xO alloys}, volume={75}, ISSN={["1077-3118"]}, DOI={10.1063/1.125340}, abstractNote={The optical and structural properties of high-quality single-crystal epitaxial MgZnO films deposited by pulsed-laser deposition were studied. In films with up to ∼36 at. % Mg incorporation, we have observed intense ultraviolet band edge photoluminescence at room temperature and 77 K. The highly efficient photoluminescence is indicative of the excitonic nature of the material. Transmission spectroscopy was used to show that the excitonic structure of the alloys was clearly visible at room temperature. High-resolution transmission electron microscopy, x-ray diffraction, and Rutherford backscattering spectroscopy/ion channeling were used to verify the epitaxial single-crystal quality of the films and characterize the defect content. Post-deposition annealing in oxygen was found to reduce the number of defects and to improve the optical properties of the films. These results indicate that MgZnO alloys have potential applications in a variety of optoelectronic devices.}, number={21}, journal={APPLIED PHYSICS LETTERS}, author={Sharma, AK and Narayan, J and Muth, JF and Teng, CW and Jin, C and Kvit, A and Kolbas, RM and Holland, OW}, year={1999}, month={Nov}, pages={3327–3329} }
 @article{hassan_sharma_narayan_muth_teng_kolbas_1999, title={Optical and structural studies of Ge nanocrystals embedded in AlN matrix fabricated by pulsed laser deposition}, volume={75}, ISSN={["1077-3118"]}, DOI={10.1063/1.124648}, abstractNote={We have fabricated Ge nanostructures buried in a matrix of AlN grown on Si(111) by pulsed laser deposition at the substrate temperature of 500 °C. The characterization of these structures was performed using high-resolution transmission electron microscopy (HRTEM), photoluminescence, and Raman spectroscopy. The HRTEM results show that the Ge islands are single crystal with a pyramidal shape. The average size of Ge islands was determined to be ∼15 nm, which could be varied by controlling laser deposition and substrate parameters. The Raman spectrum showed a peak of the Ge–Ge vibrational mode downward shifted up to 295 cm−1 which is caused by quantum confinement of phonons in the Ge dots. The photoluminescence of the Ge dots (size ∼15 nm) was blueshifted by ∼0.266 eV from the bulk Ge value of 0.73 eV at 77 K, resulting in a distinct peak at ∼1.0 eV. The transmission measurements carried out on different samples having Ge dot sizes of 7, 8, and 13 nm deposited on sapphire substrate showed the above band edge transitions of Ge, which were also blueshifted in accordance with the quantum confinement effect. The importance of pulsed laser deposition in fabricating novel nanostructures is emphasized.}, number={9}, journal={APPLIED PHYSICS LETTERS}, author={Hassan, KM and Sharma, AK and Narayan, J and Muth, JF and Teng, CW and Kolbas, RM}, year={1999}, month={Aug}, pages={1222–1224} }
 @misc{shmagin_muth_kolbas_1999, title={Optical information storage systems and methods using heterostructures comprising ternary group III-V nitride semiconductor materials}, volume={5,875,052}, number={1999 Feb. 23}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Shmagin, I. K. and Muth, J. F. and Kolbas, R. M.}, year={1999} }
 @inproceedings{teng_muth_kolbas_hassan_sharma_kvit_narayan_1999, title={Quantum confinement of above-band-bap transitions in Ge quantum dots embedded in an Al2O3 or AIN matrix}, booktitle={Optical microstructural characterization of semiconductors  (Materials Research Society proceedings, vol. 588)}, publisher={Pittsburgh, Pa.: Materials Research Society}, author={Teng, C. W. and Muth, J. F. and Kolbas, R. M. and Hassan, K. M. and Sharma, A. K. and Kvit, A. and Narayan, J.}, editor={J. Piqueras, T. Sekiguchi and Unlu, M. S.Editors}, year={1999} }
 @inproceedings{hassan_sharma_narayan_muth_teng_kolbas_1998, title={Germanium nanostructures fabricated by pulsed laser deposition}, booktitle={Microcrystalline and nanocrystalline semiconductors--1998: symposium held November 30-December 3, 1998, Boston, Massachusetts, U.S.A.}, author={Hassan, K. M. and Sharma, A. K. and Narayan, J. and Muth, J. F. and Teng, C. W. and Kolbas, R. M.}, year={1998} }
 @inproceedings{sharma_dovidenko_oktyabrsky_moxey_muth_kolbas_narayan_1998, title={Growth of high quality single crystal ZnO films on sapphire by pulsed laser ablation}, booktitle={Advances in laser ablation of materials: Symposium held April 13-16, 1998, San Francisco, California, U.S.A.  (Materials Research Society symposia proceedings ; v. 526).}, publisher={Warrendale, Pa.: Materials Research Society}, author={Sharma, A. K. and Dovidenko, K. and Oktyabrsky, S. and Moxey, D. E. and Muth, J. F. and Kolbas, R. M. and Narayan, J.}, year={1998}, pages={305} }
 @inproceedings{wei_sharma_narayan_ravindra_oktyabrsky_sankar_muth_kolbas_narayan_1998, title={Microstructure and IR range optical properties of pure DLC and DLC containing dopants prepared by pulsed laser deposition}, booktitle={Advances in laser ablation of materials: Symposium held April 13-16, 1998, San Francisco, California, U.S.A.  (Materials Research Society symposia proceedings ; v. 526).}, publisher={Warrendale, Pa.: Materials Research Society}, author={Wei, Q. and Sharma, A. K. and Narayan, R. J. and Ravindra, N. M. and Oktyabrsky, S. and Sankar, J. and Muth, J. F. and Kolbas, R. M. and Narayan, J.}, year={1998}, pages={331} }
 @inproceedings{dupuis_grudowski_eiting_shmagin_kolbas_rosner_1998, title={Optical and structural characterization of InGaN quantum-well heterostructures grown by metalorganic chemical vapor deposition}, booktitle={Compound semiconductors 1997: Proceedings of the IEEE Twenty-fourth International Symposium on Compound Semiconductors held in San Diego, California, 8-11 September 1997}, publisher={Bristol; Philadelphia: Institute of Physics Pub.}, author={Dupuis, R. D. and Grudowski, P. A. and Eiting, C. J. and Shmagin, I. K. and Kolbas, R. M. and Rosner, S. J.}, year={1998}, pages={231–234} }
 @inproceedings{shmagin_muth_kolbas_dupuis_grudowski_eiting_park_shelton_lambert_1998, title={Optical metastability in InGaN/GaN heterostructures}, booktitle={Compound semiconductors 1997: Proceedings of the IEEE Twenty-fourth International Symposium on Compound Semiconductors held in San Diego, California, 8-11 September 1997}, publisher={Bristol; Philadelphia: Institute of Physics Pub.}, author={Shmagin, I. K. and Muth, J. F. and Kolbas, R. M. and Dupuis, R. D. and Grudowski, P. A. and Eiting, C. J. and Park, J. and Shelton, B. S. and Lambert, D. J. H.}, year={1998}, pages={375–378} }
 @inproceedings{kolbas_shmagin_muth_1998, title={Optical properties of wide bandgap II-V nitride semiconductors}, booktitle={1998 5th International Conference on Solid-State and Integrated Circuit Technology: Proceedings, October 21-23, 1998, Beijing, China}, author={Kolbas, R. M. and Shmagin, I. K. and Muth, J. F.}, editor={M. Zhang and Tu, K. N.Editors}, year={1998}, pages={609–612} }
 @article{osinsky_gangopadhyay_yang_gaska_kuksenkov_temkin_shmagin_chang_muth_kolbas_1998, title={Visible-blind GaN Schottky barrier detectors grown on Si(111)}, volume={72}, ISSN={["0003-6951"]}, DOI={10.1063/1.120755}, abstractNote={We report novel GaN detectors grown by molecular beam epitaxy on Si(111) substrates. Wurtzite structure epitaxial GaN exhibits room-temperature photoluminescence with a band-edge-related emission width as narrow as 7 nm and intensities comparable to high quality layers grown on sapphire by metalorganic chemical vapor deposition. Spectral response of lateral geometry Schottky detectors shows a sharp cutoff at 365 nm with peak responsivities of ∼0.05 A/W at 0 V, and ∼0.1 A/W with a −4 V bias. The dark current is ∼60 nA at −2 V bias. The noise equivalent power is estimated to be 3.7×10−9 W over the response bandwidth of 2.2 MHz.}, number={5}, journal={APPLIED PHYSICS LETTERS}, author={Osinsky, A and Gangopadhyay, S and Yang, JW and Gaska, R and Kuksenkov, D and Temkin, H and Shmagin, IK and Chang, YC and Muth, JF and Kolbas, RM}, year={1998}, month={Feb}, pages={551–553} }
 @article{muth_lee_shmagin_kolbas_casey_keller_mishra_denbaars_1997, title={Absorption coefficient, energy gap, exciton binding energy, and recombination lifetime of GaN obtained from transmission measurements}, volume={71}, ISSN={["0003-6951"]}, DOI={10.1063/1.120191}, abstractNote={The absorption coefficient for a 0.4-μm-thick GaN layer grown on a polished sapphire substrate was determined from transmission measurements at room temperature. A strong, well defined exciton peak for the A and B excitons was obtained. The A, B, and C excitonic features are clearly defined at 77 K. At room temperature, an energy gap Eg=3.452±0.001 eV and an exciton binding energy ExA,B=20.4±0.5 meV for the A and B excitons and ExC=23.5±0.5 meV for the C exciton were determined by analysis of the absorption coefficient. From this measured absorption coefficient, together with the detailed balance approach of van Roosbroek and Shockley, the radiative constant B=1.1×10−8 cm3/s was obtained.}, number={18}, journal={APPLIED PHYSICS LETTERS}, author={Muth, JF and Lee, JH and Shmagin, IK and Kolbas, RM and Casey, HC and Keller, BP and Mishra, UK and DenBaars, SP}, year={1997}, month={Nov}, pages={2572–2574} }
 @article{keller_keller_kapolnek_mishra_denbaars_shmagin_kolbas_krishnankutty_1997, title={Growth of bulk InGaN films and quantum wells by atmospheric pressure metalorganic chemical vapour deposition}, volume={170}, ISSN={["0022-0248"]}, DOI={10.1016/S0022-0248(96)00553-2}, abstractNote={InGaN bulk layers and single quantum wells were grown on 1.4 to 2.4 μm thick GaN on sapphire films by atmospheric pressure metalorganic chemical vapour deposition (AP-MOCVD). The morphology of the epitaxial layers was strongly affected by the VIII ratio in the gas phase. The incorporation efficiency of indium was observed to increase with higher growth rates and decreasing temperature, but was independent of the VIII ratio in the investigated parameter range. In0.16Ga0.84N single quantum wells showed intense quantum well related luminescence at room temperature, with a full width at half maximum of 7.9 nm at a thickness of 50 Å. Single quantum wells embedded in InGaN of graded composition showed superior properties compared to quantum wells with In0.04Ga0.94N barriers of constant composition.}, number={1-4}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Keller, S and Keller, BP and Kapolnek, D and Mishra, UK and DenBaars, SP and Shmagin, IK and Kolbas, RM and Krishnankutty, S}, year={1997}, month={Jan}, pages={349–352} }
 @article{zavada_abernathy_pearton_mackenzie_mileham_wilson_schwartz_haggerottcrawford_shul_kilcoyne_et al._1997, title={Microdisk laser structures formed in III-V nitride epilayers}, volume={41}, ISSN={["0038-1101"]}, DOI={10.1016/S0038-1101(96)00244-4}, abstractNote={Several kinds of nitride-based micro-resonators have been fabricated. Firstly, a microdisk laser structure comprising three InGaNGaN quantum wells on a thick AlN buffer has been grown by metal-organic molecular beam epitaxy and fabricated using a combination of non-selective Cl2/CH4/H2/Ar dry etching and selective KOH-based wet etching of the AlN. These structures are of potential use in short wavelength photonic or optoelectronic circuits. In a second structure Er was implanted into a GaN layer to produce strong emission at 1.54 μm. Similar results have been obtained in Er-implanted AlN, and AlN doped during epitaxial growth.}, number={2}, journal={SOLID-STATE ELECTRONICS}, author={Zavada, JM and Abernathy, CR and Pearton, SJ and Mackenzie, JD and Mileham, JR and Wilson, RG and Schwartz, RN and HaggerottCrawford, M and Shul, RJ and Kilcoyne, SP and et al.}, year={1997}, month={Feb}, pages={353–357} }
 @article{shmagin_muth_kolbas_krishnankutty_keller_mishra_denbaars_1997, title={Observation of lasing from photopumped InGaN/GaN heterostructures in an edge emitting configuration}, volume={81}, ISSN={["0021-8979"]}, DOI={10.1063/1.364058}, abstractNote={Optically pumped lasing from InGaN/GaN single heterojunctions (SH) was observed in an edge emitting configuration at 77 K. The heterojunctions were grown by atmospheric pressure metalorganic chemical vapor deposition on c-plane sapphire substrates. The frequency tripled output of a mode-locked titanium:sapphire laser with a pulse width of 250 fs, operating at 280 nm, was used as the photoexcitation source. The nonlinear dependence of output emission intensity on input power density, the observations of a strongly polarized output emission, and distinct Fabry–Perot modes are discussed.}, number={4}, journal={JOURNAL OF APPLIED PHYSICS}, author={Shmagin, IK and Muth, JF and Kolbas, RM and Krishnankutty, S and Keller, S and Mishra, UK and DenBaars, SP}, year={1997}, month={Feb}, pages={2021–2023} }
 @article{shmagin_muth_kolbas_dupuis_grudowski_eiting_park_shelton_lambert_1997, title={Optical data storage in InGaN/GaN heterostructures}, volume={71}, ISSN={["0003-6951"]}, DOI={10.1063/1.119900}, abstractNote={Optical storage data was realized using an InGaN/GaN single heterostructure. It was observed that exposure to a high power density ultraviolet light temporarily changes the optical properties of the InGaN epitaxial layer. The photo-induced changes can be observed under an optical microscope with low intensity ultraviolet excitation. This effect was used to create high contrast optical patterns on the sample at room temperature and 77 K. The photo-induced changes completely disappear in about four hours at room temperature. After the recorded pattern is erased, the information can be rewritten without a change in efficiency or retention time.}, number={10}, journal={APPLIED PHYSICS LETTERS}, author={Shmagin, IK and Muth, JF and Kolbas, RM and Dupuis, RD and Grudowski, PA and Eiting, CJ and Park, J and Shelton, BS and Lambert, DJH}, year={1997}, month={Sep}, pages={1382–1384} }
 @article{shmagin_muth_lee_kolbas_balkas_sitar_davis_1997, title={Optical metastability in bulk GaN single crystals}, volume={71}, ISSN={["0003-6951"]}, DOI={10.1063/1.119577}, abstractNote={Bulk GaN single crystals were grown from cold pressed GaN powder by sublimation in flowing ammonia. Optical transmission measurements indicated that the absorption coefficient for the transparent samples is 50 cm−1 in the wavelength region from 650 to 400 nm. Optical metastability in bulk GaN crystals was studied through time dependent photoluminescence both at room and liquid–nitrogen temperatures. The observation included decreasing output intensity of the ultraviolet emission attributed to the band edge and increasing output intensity of a new emission band centered at 378 nm at room temperature. At liquid–nitrogen temperature, the photoinduced emission band consisted of at least one LO-phonon replica of the zero-phonon line centered at 378 nm. The ratio of output intensities of the photoinduced band to the band edge increased by a factor of 10 during 27 min of exposure time. The photoinduced effect is attributed to the metastable nature of traps in bulk GaN.}, number={4}, journal={APPLIED PHYSICS LETTERS}, author={Shmagin, IK and Muth, JF and Lee, JH and Kolbas, RM and Balkas, CM and Sitar, Z and Davis, RF}, year={1997}, month={Jul}, pages={455–457} }
 @article{shmagin_muth_kolbas_krishnankutty_keller_abare_coldren_mishra_denbaars_1997, title={Photoluminescence characteristics of GaN/InGaN/GaN quantum wells}, volume={26}, ISSN={["0361-5235"]}, DOI={10.1007/s11664-997-0172-y}, number={3}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={Shmagin, IK and Muth, JF and Kolbas, RM and Krishnankutty, S and Keller, S and Abare, AC and Coldren, LA and Mishra, UK and DenBaars, SP}, year={1997}, month={Mar}, pages={325–329} }
 @article{shen_shmagin_koch_kolbas_fahmy_bergman_nemanich_mcclure_sitar_quan_1997, title={Photoluminescence from mechanically milled Si and SiO2 powders}, volume={55}, ISSN={["0163-1829"]}, DOI={10.1103/physrevb.55.7615}, abstractNote={The photoluminescence (PL) in as-received and milled Si and SiO2 powder is reported. The Si and SiO2 powder is characterized by chemical analysis, Raman scattering, x-ray photoelectron spectra, infrared absorption, x-ray diffraction, and differential thermal analysis. The results indicate that the Si powder has amorphous Si oxide and suboxide surface layers. The milling of Si powder results in the formation of nanocrystalline/amorphous Si components. An amorphous SiO2 component is formed by milling crystalline SiO2. The PL spectra for as-received Si, milled Si, and SiO2 powder exhibit similar peak shapes, peak maxima, and full width at half maximum values. For both the as-received and the milled Si powder, experimental results appear to exclude mechanisms for PL related to an amorphous Si component or Si-H or Si-OH bonds, or the quantum confinement effect. Similarly, for milled SiO2 powder mechanisms for PL do not appear related to Si-H or Si-OH bonds. Instead the greatly increased intensity of PL for milled SiO2 can be related to both the increased volume fraction of the amorphous SiO2 component and the increased density of defects introduced in the amorphous SiO2 upon milling. It is suggested that the PL for as-received Si, milling-induced nanocrystalline/amorphous Si, and milled SiO2 results from defects, such as the nonbridging oxygen hole center, in the amorphous Si suboxide and/or SiO2 components existing in these powder samples. The PL measurement for milled SiO2 is dependent on air pressure whereas that for as-received SiO2 is not, suggesting that new emitting centers are formed by milling.}, number={12}, journal={PHYSICAL REVIEW B}, author={Shen, TD and Shmagin, I and Koch, CC and Kolbas, RM and Fahmy, Y and Bergman, L and Nemanich, RJ and McClure, MT and Sitar, Z and Quan, MX}, year={1997}, month={Mar}, pages={7615–7623} }
 @article{shmagin_muth_kolbas_mack_abare_keller_coldren_mishra_denbaars_1997, title={Reconfigurable optical properties in InGaN/GaN quantum wells}, volume={71}, ISSN={["0003-6951"]}, DOI={10.1063/1.119935}, abstractNote={Reconfigurable optical properties were studied in InGaN/GaN multiple quantum well (MQW) structures. It was observed that a short time exposure to a high intensity ultraviolet light results in long term, but reversible changes of the optical properties of InGaN/GaN MQW samples. The photoinduced changes can be observed using an optical microscope under low intensity ultraviolet light and are visible as a high contrast pattern. The retention time at room temperature for 12 and 20 MQW samples was longer than five days and four weeks, respectively. The effect was studied at room and cryogenic temperatures.}, number={11}, journal={APPLIED PHYSICS LETTERS}, author={Shmagin, IK and Muth, JF and Kolbas, RM and Mack, MP and Abare, AC and Keller, S and Coldren, LA and Mishra, UK and DenBaars, SP}, year={1997}, month={Sep}, pages={1455–1457} }
 @inproceedings{balkas_sitar_zheleva_bergman_shmagin_muth_kolbas_nemanich_davis_1996, title={Growth of bulk AIN and GaN single crystals by sublimation}, booktitle={III-V nitrides: symposium held December 2-6, 1996, Boston, Massachusetts, U.S.A.  (Materials Research Society symposia proceedings ; v. 449)}, publisher={Pittsburgh, Pa.: Materials Research Society}, author={Balkas, C. M. and Sitar, Z. and Zheleva, T. and Bergman, L. and Shmagin, I. K. and Muth, J. F. and Kolbas, R. M. and Nemanich, R. and Davis, R. F.}, year={1996}, pages={41–46} }
 @inbook{kolbas_1996, title={Quantum well heterostructure lasers}, booktitle={Properties of gallium arsenide (3rd ed.) (Datareviews series, no. 16)}, publisher={INSPEC}, author={Kolbas, R. M.}, editor={M. R. Brozel and Stillman, G. E.Editors}, year={1996}, pages={887–905} }
 @inbook{shmagin_muth_kolbas_krishnankkutty_keller_mishra_denbaars_1996, title={Stimulated emission and gain measurements from InGaN/GaN heterostructures}, booktitle={III-V nitrides: Symposium held December 2-6, 1996, Boston, Massachusetts, U.S.A.(Materials Research Society symposia proceedings ; v. 449)}, publisher={Pittsburgh, Pa.: Materials Research Society}, author={Shmagin, I. K. and Muth, J. F. and Kolbas, R. M. and Krishnankkutty, S. and Keller, S. and Mishra, U. K. and DenBaars, S. P.}, year={1996}, pages={1209–1214} }
 @misc{carney_kolbas_1987, title={Integrated quantum well lasers for wavelength division multiplexing}, volume={4,637,122}, number={1987 Jan. 10}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Carney, J. K. and Kolbas, R. M.}, year={1987} }
 @misc{carney_kolbas_1986, title={Integrated quantum well lasers for wavelength division multiplexing}, volume={4,577,321}, number={1986 Mar. 18}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Carney, J. K. and Kolbas, R. M.}, year={1986} }
 @misc{kolbas_1985, title={Method of fabricating emitter/detector-in-a-well for the integration of electronic and optoelectronic components}, volume={4,532,694}, number={1985 Aug. 6}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Kolbas, R. M.}, year={1985} }