@article{lai_paskova_wheeler_chung_grenko_johnson_udwary_preble_evans_2012, title={Indium incorporation in InGaN/GaN quantum wells grown on m-plane GaN substrate and c-plane sapphire}, volume={209}, ISSN={["1862-6319"]}, DOI={10.1002/pssa.201127345}, abstractNote={Abstract}, number={3}, journal={PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE}, author={Lai, K. Y. and Paskova, T. and Wheeler, V. D. and Chung, T. Y. and Grenko, J. A. and Johnson, M. A. L. and Udwary, K. and Preble, E. A. and Evans, K. R.}, year={2012}, month={Mar}, pages={559–564} }
 @article{wang_sun_chua_johnson_2011, title={Comparative investigation of photoluminescence of In- and Si-doped GaN/A1GaN multi-quantum wells (Retraction of Vol 97, Pg 196, 2003)}, volume={176}, ISSN={["1873-4944"]}, DOI={10.1016/j.mseb.2011.03.009}, number={9}, journal={MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS}, author={Wang, L. S. and Sun, W. H. and Chua, S. J. and Johnson, Mark}, year={2011}, month={May}, pages={772–772} }
 @article{jur_wheeler_lichtenwalner_maria_johnson_2011, title={Epitaxial growth of lanthanide oxides La2O3 and Sc2O3 on GaN}, volume={98}, ISSN={["0003-6951"]}, DOI={10.1063/1.3541883}, abstractNote={Deposition of lanthanide oxides on GaN is investigated as a means to produce stable dielectric with good interface quality. Epitaxial growth of cubic ⟨111⟩-oriented Sc2O3 is observed on GaN [0001] with a lattice mismatch of 7.2%, whereas La2O3 growth, with a lattice mismatch of ∼21%, results in a mixed phase epitaxial film comprised of the bixbyite and hexagonal allotropes. Substantial roughening accompanies this mixed phase film. By inserting a thin Sc2O3 interfacial layer between La2O3 and GaN and a Sc2O3 capping layer, the crystal quality of the predominantly La2O3 layer is improved and the stack is stabilized against hydroxide formation under ambient conditions.}, number={4}, journal={APPLIED PHYSICS LETTERS}, author={Jur, Jesse S. and Wheeler, Virginia D. and Lichtenwalner, Daniel J. and Maria, Jon-Paul and Johnson, Mark A. L.}, year={2011}, month={Jan} }
 @article{park_ozbek_ma_veety_morgensen_barlage_wheeler_johnson_2010, title={An analytical model of source injection for N-type enhancement mode GaN-based Schottky Source/Drain MOSFET's with experimental demonstration}, volume={54}, ISSN={["0038-1101"]}, DOI={10.1016/j.sse.2010.06.013}, abstractNote={Abstract This study investigates the effect of the Gate-to-Source/Drain overlap structure of a GaN Schottky Source/Drain MOSFET. The Gate-to-Source overlap structure of the device allows the gate electric field to reduce the height of the Nickel(source)–GaN Schottky barrier near the SiO 2 –GaN interface at the source side, injecting more thermionically generated carriers over the partially reduced Schottky barrier. Based on this Schottky barrier lowering mechanism, an analytical model was developed. The analytical model shows that the reduction of the Schottky barrier height by 0.25 eV increases the on-state drain current by two orders of magnitude, which is in agreement of the previously reported TCAD simulation result in [6] . A specifically designed GaN Schottky Source/Drain MOSFET with the Gate-to-Source/Drain overlap structure was fabricated and characterized; the I D – V DS characteristic of the device shows that the on-state drain current of the device was increased by up to 160× compared to the same kind of device without the overlap structure (reported in Lei Ma (2007) [7] ), which is in agreement with the analytical model described herein.}, number={12}, journal={SOLID-STATE ELECTRONICS}, author={Park, Jaehoon and Ozbek, Ayse M. and Ma, Lei and Veety, Matthew T. and Morgensen, Michael P. and Barlage, Douglas W. and Wheeler, Virginia D. and Johnson, Mark A. L.}, year={2010}, month={Dec}, pages={1680–1685} }
 @article{lai_paskova_wheeler_grenko_johnson_udwary_preble_evans_2010, title={Effect of m-plane GaN substrate miscut on InGaN/GaN quantum well growth}, volume={312}, ISSN={["1873-5002"]}, DOI={10.1016/j.jcrysgro.2010.01.020}, abstractNote={The effect of m-plane GaN substrate miscut on the growth of InGaN/GaN quantum wells (QWs) was investigated. It was found that the miscut toward [0 0 0 1] c+-axis resulted in an increase of In incorporation efficiency and in a green-shift of the QW emission, while the miscut toward [1 1 2 0] a-axis resulted in even higher In compositions but it also led to an increased epitaxial surface roughness and deterioration of the QW structures. The results indicated that miscut toward a-axis is undesirable while miscut toward c+-axis is beneficial for achieving longer wavelength emission in QWs grown on m-plane GaN substrates.}, number={7}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Lai, K. Y. and Paskova, T. and Wheeler, V. D. and Grenko, J. A. and Johnson, M. A. L. and Udwary, K. and Preble, E. A. and Evans, K. R.}, year={2010}, month={Mar}, pages={902–905} }
 @article{grenko_ebert_reynolds_duscher_barlage_johnson_preble_paskova_evans_2010, title={Optimization of homoepitaxially grown AlGaN/GaN heterostructures}, volume={207}, ISSN={["1862-6300"]}, DOI={10.1002/pssa.200925508}, abstractNote={Abstract}, number={10}, journal={PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE}, author={Grenko, J. A. and Ebert, C. W. and Reynolds, C. L., Jr. and Duscher, G. J. and Barlage, D. W. and Johnson, M. A. L. and Preble, E. A. and Paskova, T. and Evans, K. R.}, year={2010}, month={Oct}, pages={2292–2299} }
 @article{wang_alur_sharma_tong_thapa_gartland_issacs-smith_ahyi_williams_park_et al._2010, title={Ultra-low leakage and high breakdown Schottky diodes fabricated on free-standing GaN substrate}, volume={26}, ISSN={0268-1242 1361-6641}, url={http://dx.doi.org/10.1088/0268-1242/26/2/022002}, DOI={10.1088/0268-1242/26/2/022002}, abstractNote={Vertical Schottky diodes were fabricated on the bulk GaN substrate with decreasing impurity concentration from N-face to Ga-face. An array of circular Pt Schottky contacts and a full backside Ti/Al/Ni/Au ohmic contact were prepared on the Ga-face and the N-face of the n-GaN substrate, respectively. The Schottky diode exhibits a minimum specific on-state resistance of 1.3 mΩ cm2 and a maximum breakdown voltage of 600 V, resulting in a figure-of- merit of 275 MW cm−2. An ultra-low reverse leakage current density of 3.7 × 10−4 A cm−2 at reverse bias of 400 V was observed. Temperature-dependent I–V measurements were also carried out to study the forward and reverse transportation mechanisms.}, number={2}, journal={Semiconductor Science and Technology}, publisher={IOP Publishing}, author={Wang, Yaqi and Alur, Siddharth and Sharma, Yogesh and Tong, Fei and Thapa, Resham and Gartland, Patrick and Issacs-Smith, Tamara and Ahyi, Claude and Williams, John and Park, Minseo and et al.}, year={2010}, month={Dec}, pages={022002} }
 @article{lai_paskova_wheeler_grenko_johnson_barlage_udwary_preble_evans_2009, title={Excitation current dependent cathodoluminescence study of InGaN/GaN quantum wells grown on m-plane and c-plane GaN substrates}, volume={106}, ISSN={["1089-7550"]}, DOI={10.1063/1.3264729}, abstractNote={InGaN/GaN quantum wells (QWs) grown with identical conditions on m-plane and c-plane GaN substrates were studied by cathodoluminescence spectroscopy. At a low current of 10 nA, the emission intensity and wavelength of the m-plane aligned QWs were found to be about two times stronger and 19.5 nm blueshifted with respect to that of the c-plane aligned QWs. An increase in the current over three orders of magnitude was found to result in an increase in the emission intensities, with faster saturation in the m-plane aligned QWs. This was explained by the screening of quantum-confined Stark effect in the emission efficiency of the c-plane aligned QWs.}, number={11}, journal={JOURNAL OF APPLIED PHYSICS}, author={Lai, K. Y. and Paskova, T. and Wheeler, V. D. and Grenko, J. A. and Johnson, M. A. L. and Barlage, D. W. and Udwary, K. and Preble, E. A. and Evans, K. R.}, year={2009}, month={Dec} }
 @article{saripalli_pei_biggerstaff_ramachandran_duscher_johnson_zeng_dandu_jin_barlage_2007, title={Transmission electron microscopy studies of regrown GaN Ohmic contacts on patterned substrates for metal oxide semiconductor field effect transistor applications}, volume={90}, ISSN={["1077-3118"]}, DOI={10.1063/1.2741123}, abstractNote={Contact selected area regrowth of GaN was performed by metal organic chemical vapor deposition using a silicon nitride dielectric hard mask to define plasma etched recesses and to define source-drain regions. A low temperature regrowth process at 750–850°C was adopted to limit lateral overgrowth. High resolution electron microscopy images and selected area diffraction confirmed the regrowth selectivity and revealed that the low temperature regrown GaN is epitaxial and has a wurtzite crystal structure. I-V characteristics of the fabricated metal oxidesemiconductor field effect transistor show enhancement mode operation.}, number={20}, journal={APPLIED PHYSICS LETTERS}, author={Saripalli, Y. N. and Pei, L. and Biggerstaff, T. and Ramachandran, S. and Duscher, G. J. and Johnson, M. A. L. and Zeng, C. and Dandu, K. and Jin, Y. and Barlage, D. W.}, year={2007}, month={May} }
 @article{wang_park_saripalli_johnson_zeng_barlage_long_2006, title={Optical spectroscopic analysis of selected area epitaxially regrown n(+) gallium nitride}, volume={99}, ISSN={["1089-7550"]}, DOI={10.1063/1.2204755}, abstractNote={Gallium nitride (GaN) metal-insulator-semiconductor field-effect transistor with regrown by selected area metal organic vapor-phase-epitaxy n+ layer has been analyzed by micro-Raman and microphotoluminescence (micro-PL) spectroscopy. The material properties of the regrown n+ layer and the intrinsic layer in the gate region were extracted by using both spectroscopies. The free-carrier concentration of the regrown GaN layer and the intrinsic layer were determined by line shape analysis of the coupled plasmon-phonon mode to be 4.7×1017 and <3×1016cm−3, respectively. The inefficient substitutions of Ga vacancy (VGa) by Si result in relatively low carrier concentration in the regrown GaN layer. From the shift of E2(2) Raman peak and the near-band-edge (NBE) PL peak, the biaxial compressive stress in the intrinsic layer was found to be 0.4GPa. The residual stress was found to be fully relaxed in the regrown layer. The Si doping concentration in the regrown layer was determined to be 2×1019cm−3 based on the potential fluctuations introduced redshift of its NBE PL peak.}, number={12}, journal={JOURNAL OF APPLIED PHYSICS}, author={Wang, D. and Park, M. and Saripalli, Y. N. and Johnson, M. A. L. and Zeng, C. and Barlage, D. W. and Long, J. P.}, year={2006}, month={Jun} }
 @article{saripalli_zeng_long_barlage_johnson_braddock_2006, title={Properties of III-N MOS structures with low-temperature epitaxially regrown ohmic contacts}, volume={287}, ISSN={["1873-5002"]}, DOI={10.1016/j.jcrysgro.2005.10.075}, abstractNote={A significant limitation in the fabrication of III-N MOSFET relates to the formation of ohmic contacts for enhancement-mode MOSFET structures. Unlike existing III-N HFET devices, which include a high free-carrier density two-dimensional electron gas (2DEG) in the semiconductor substrate, a MOSFET in either accumulation or inversion mode require low free-carrier concentrations for the semiconductor channel to have an off-state. The applied gate bias enhances the free-carrier density in the channel, turning on the FET. Unfortunately, a low free-carrier density substrate is problematic for the formation of ohmic contacts, a problem usually dealt with in silicon MOS through self-aligned ion implantation. The high annealing temperatures associated with activating implanted dopants to substitutional sites limits the use of ion implantation for III-N MOSFET fabrication. To overcome this difficulties, selected area epitaxial re-growth of doped III-N materials was developed to form source-drain contacts on otherwise low-doped III-N epitaxial substrates, yielding the needed N+/n−/N+ or N+/p−/N+ structures. Contact re-growth was performed by MOVPE using a silicon nitride dielectric mask defining plasma-etched recesses in the source-drain region. A significant acceleration in the growth rate and surface roughening was observed following re-growth relative to a non-selective area epitaxial growth due to the reduced fill-factor, motivating a general change in MOVPE-operating conditions during re-growth. As the re-growth was intentionally designed to limit the lateral extent of the source-drain regions, the MOVPE re-growth process was performed under conditions limiting lateral overgrowth. III-N MOSFET structures with epitaxial regrown contacts are projected to provide a pathway for low threshold voltage devices suitable for amplifier or logic applications.}, number={2}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Saripalli, YN and Zeng, C and Long, JP and Barlage, DW and Johnson, MAL and Braddock, D}, year={2006}, month={Jan}, pages={562–565} }
 @article{sonkusale_amsinck_nackashi_di spigna_barlage_johnson_franzon_2005, title={Fabrication of wafer scale, aligned sub-25 nm nanowire and nanowire templates using planar edge defined alternate layer process}, volume={28}, ISSN={["1873-1759"]}, DOI={10.1016/j.physe.2005.01.010}, abstractNote={We have demonstrated a new planar edge defined alternate layer (PEDAL) process to make sub-25 nm nanowires across the whole wafer. The PEDAL process is useful in the fabrication of metal nanowires directly onto the wafer by shadow metallization and has the ability to fabricate sub-10 nm nanowires with 20 nm pitch. The process can also be used to make templates for the nano-imprinting with which the crossbar structures can be fabricated. The process involves defining the edge by etching a trench patterned by conventional i-line lithography, followed by deposition of alternating layers of silicon nitride and crystallized a-Si. The thickness of these layers determines the width and spacing of the nanowires. Later the stack is planarized to the edge of the trench by spinning polymer Shipley 1813 and then dry etching the polymer, nitride and polysilicon stack with non-selective RIE etch recipe. Selective wet etch of either nitride or polysilicon gives us the array of an aligned nanowires template. After shadow metallization of the required metal, we get metal nanowires on the wafer. The process has the flexibility of routing the nanowires around the logic and memory modules all across the wafer. The fabrication facilities required for the process are readily available and this process provides the great alternative to existing slow and/or costly nanowire patterning techniques.}, number={2}, journal={PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES}, author={Sonkusale, SR and Amsinck, CJ and Nackashi, DP and Di Spigna, NH and Barlage, D and Johnson, M and Franzon, PD}, year={2005}, month={Jul}, pages={107–114} }
 @article{wang_sun_chua_johnson_2003, title={Comparative investigation of photoluminescence of In- and Si- doped GaN/AlGaN multi-quantum wells}, volume={97}, ISSN={["0921-5107"]}, DOI={10.1016/s0921-5107(02)00572-x}, abstractNote={This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief and author, as the authors have plagiarized part of a paper that had already appeared in Mater. Res. Soc. Symp. Proc., 719 (2002) 371–376. One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and has not appeared in a publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.}, number={2}, journal={MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY}, author={Wang, LS and Sun, WH and Chua, SJ and Johnson, M}, year={2003}, month={Jan}, pages={196–199} }
 @article{oberhofer_muth_johnson_chen_fleet_cooper_2003, title={Planar gallium nitride ultraviolet optical modulator}, volume={83}, ISSN={["0003-6951"]}, DOI={10.1063/1.1615675}, abstractNote={A planar optical modulator operating near 360 nm suitable for ultraviolet spatial light modulation has been constructed. The modulator operates in transmission mode with a 18% change in transmission at 305 V. The modulator is based on using the electric field to shift and broaden the room-temperature resonance of the gallium nitride exciton with electric fields.}, number={14}, journal={APPLIED PHYSICS LETTERS}, author={Oberhofer, AE and Muth, JF and Johnson, MAL and Chen, ZY and Fleet, EF and Cooper, GD}, year={2003}, month={Oct}, pages={2748–2750} }
 @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{johnson_yu_brown_koeck_el-masry_kong_edmond_cook_schetzina_1999, title={A critical comparison between MOVPE and MBE growth of III-V nitride semiconductor materials for opto-electronic device applications}, volume={4S1}, DOI={10.1557/s1092578300003100}, abstractNote={A systematic study of the growth and doping of GaN, AlGaN, and InGaN by both molecular beam epitaxy (MBE) and metal-organic vapor phase epitaxy (MOVPE) has been performed. Critical differences between the resulting epitaxy are observed in the p-type doping using magnesium as the acceptor species. MBE growth, using rf-plasma sources to generate the active nitrogen species for growth, has been used for III-Nitride compounds doped either n-type with silicon or p-type with magnesium. Blue and violet light emitting diode (LED) test structures were fabricated. These vertical devices required a relatively high forward current and exhibited high leakage currents. This behavior was attributed to parallel shorting mechanisms along the dislocations in MBE grown layers. For comparison, similar devices were fabricated using a single wafer vertical flow MOVPE reactor and ammonia as the active nitrogen species. MOVPE grown blue LEDs exhibited excellent forward device characteristics and a high reverse breakdown voltage. We feel that the excess hydrogen, which is present on the GaN surface due to the dissociation of ammonia in MOVPE, acts to passivate the dislocations and eliminate parallel shorting for vertical device structures. These findings support the widespread acceptance of MOVPE, rather than MBE, as the epitaxial growth technique of choice for III-V nitride materials used in vertical transport bipolar devices for optoelectronic applications.}, number={G5.10}, journal={MRS Internet Journal of Nitride Semiconductor Research}, author={Johnson, M. A. L. and Yu, Z. H. and Brown, J. D. and Koeck, F. A. and El-Masry, N. A. and Kong, H. S. and Edmond, J. A. and Cook, J. W. and Schetzina, J. F.}, year={1999} }
 @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{yu_johnson_brown_el-masry_muth_cook_schetzina_haberern_kong_edmond_1999, title={Epitaxial lateral overgrowth of GaN on SiC and sapphire substrates}, volume={4S1}, DOI={10.1557/s1092578300002878}, abstractNote={The epitaxial lateral overgrowth (ELO) process for GaN has been studied using SiC and sapphire substrates. Both MBE and MOVPE growth processes were employed in the study. The use of SiO2 versus SiNx insulator stripes was investigated using window/stripe widths ranging from 20 μm/4 μm to 3 μm/15 μm. GaN film depositions were completed at temperatures ranging from 800 °C to 1120 °C. Characterization experiments included RHEED, TEM, SEM and cathodolumenescence studies. The MBE growth experiments produced polycrystalline GaN over the insulator stripes even at deposition temperatures as high as 990 °C. In contrast, MOVPE growth produced single-crystal GaN stripes with no observable threading dislocations.}, number={G4.3}, journal={MRS Internet Journal of Nitride Semiconductor Research}, author={Yu, Z. H. and Johnson, M. A. L. and Brown, J. D. and El-Masry, N. A. and Muth, J. F. and Cook, J. W. and Schetzina, J. F. and Haberern, K. W. and Kong, H. S. and Edmond, J. S.}, year={1999} }
 @article{johnson_1999, title={Pre-television stereotypes: Mexicans in US newsreels, 1919-1932}, volume={16}, ISSN={["0739-3180"]}, DOI={10.1080/15295039909367109}, abstractNote={This study explored images of Mexicans and dominant symbols in early U.S. newsreels, whether they changed throughout the 1920s, and whether they reflected the era's film stereotypes. Dominant images were dignitaries, doers, beauties, bystanders, and clerics. Symbols of modernity and class outweighed traditional images. Negative symbols like dirt or weapons were not prevalent. After 1924, symbols of literacy, diplomacy, and construction were more visible. The study provides an historical context for Latino television news images today. In addition, it reflects mass media's role in reinforcing modernity and spectatorship‐allowing power of the gaze comparisons between modern and postmodern eras.}, number={4}, journal={CRITICAL STUDIES IN MASS COMMUNICATION}, author={Johnson, MA}, year={1999}, month={Dec}, pages={417–435} }
 @article{guha_bojarczuk_johnson_schetzina_1999, title={Selective area metalorganic molecular-beam epitaxy of GaN and the growth of luminescent microcolumns on Si/SiO2}, volume={75}, ISSN={["0003-6951"]}, DOI={10.1063/1.124409}, abstractNote={We demonstrate the selective area growth of gallium nitride on patterned Si(111)/GaN/SiO2 wafers by metalorganic molecular beam epitaxy using triethyl gallium as a Ga source. We show that such selective area deposition may be used to grow isolated microcolumns of GaN with lateral dimensions of tens of nanometers on Si/SiO2 wafers. Via high resolution cathodoluminescence imaging we show that such microcolumn structures are highly luminescent inspite of a large surface to volume ratio, indicating that nonradiative recombination at free surfaces is not a significant issue in this system.}, number={4}, journal={APPLIED PHYSICS LETTERS}, author={Guha, S and Bojarczuk, NA and Johnson, MAL and Schetzina, JF}, year={1999}, month={Jul}, pages={463–465} }