@misc{roberts_parker_muth_leboeuf_aumer_bedair_reed_2002, title={Ultraviolet-visible metal-semiconductor-metal photodetectors fabricated from InxGa1-xN (0 <= x <= 0.13)}, volume={31}, number={1}, journal={Journal of Electronic Materials}, author={Roberts, J. C. and Parker, C. A. and Muth, J. F. and Leboeuf, S. F. and Aumer, M. E. and Bedair, S. M. and Reed, M. J.}, year={2002}, month={Jan}, pages={L1–6} }
 @article{reed_el-masry_stadelmaier_ritums_reed_parker_roberts_bedair_2001, title={Room temperature ferromagnetic properties of (Ga, Mn)N}, volume={79}, ISSN={["1077-3118"]}, DOI={10.1063/1.1419231}, abstractNote={Dilute magnetic semiconductor GaN with a Curie temperature above room temperature has been achieved by manganese doping. By varying the growth and annealing conditions of Mn-doped GaN we have identified Curie temperatures in the range of 228–370 K. These Mn-doped GaN films have ferromagnetic behavior with hysteresis curves showing a coercivity of 100–500 Oe. Structure characterization by x-ray diffraction and transmission electron microscopy indicated that the ferromagnetic properties are not a result of secondary magnetic phases.}, number={21}, journal={APPLIED PHYSICS LETTERS}, author={Reed, ML and El-Masry, NA and Stadelmaier, HH and Ritums, MK and Reed, MJ and Parker, CA and Roberts, JC and Bedair, SM}, year={2001}, month={Nov}, pages={3473–3475} }
 @article{reed_ritums_stadelmaier_reed_parker_bedair_el-masry_2001, title={Room temperature magnetic (Ga,Mn)N: a new material for spin electronic devices}, volume={51}, ISSN={["0167-577X"]}, DOI={10.1016/S0167-577X(01)00342-1}, abstractNote={A new dilute magnetic semiconductor (Ga,Mn)N grown by metal organic chemical vapor deposition (MOCVD) is reported. Vibrating sample magnetometer (VSM) and extraordinary Hall effect (EHE) measurements verified a ferromagnetic component at room temperature. The direction of the easy axis and the Curie temperature varies with the growth conditions, the latter ranging from 38°C to 75°C. Secondary ion mass spectroscopy (SIMS) confirms diffusion of Mn into the GaN to a depth of 380 Å.}, number={6}, journal={MATERIALS LETTERS}, author={Reed, ML and Ritums, MK and Stadelmaier, HH and Reed, MJ and Parker, CA and Bedair, SM and El-Masry, NA}, year={2001}, month={Dec}, pages={500–503} }
 @article{alexson_bergman_nemanich_dutta_stroscio_parker_bedair_el-masry_adar_2001, title={Ultraviolet raman study of A(1)(LO) and E-2 phonons in InxGa1-xN alloys}, volume={89}, ISSN={["0021-8979"]}, DOI={10.1063/1.1330760}, abstractNote={We report on ultraviolet Raman spectroscopy of InxGa1−xN thin films grown on sapphire by metal-organic chemical vapor deposition. The A1(LO) and E2 phonon mode behavior was investigated over a large compositional range (0<x<0.50). Compelling evidence is presented for one-mode behavior for the A1(LO) phonon, and data suggestive of two-mode behavior are presented for the E2 phonon.}, number={1}, journal={JOURNAL OF APPLIED PHYSICS}, author={Alexson, D and Bergman, L and Nemanich, RJ and Dutta, M and Stroscio, MA and Parker, CA and Bedair, SM and El-Masry, NA and Adar, F}, year={2001}, month={Jan}, pages={798–800} }
 @article{reed_el-masry_parker_roberts_bedair_2000, title={Critical layer thickness determination of GaN/InGaN/GaN double heterostructures}, volume={77}, DOI={10.1063/1.1334361}, abstractNote={We report on the critical layer thickness of GaN/InxGa1−xN/GaN double heterostructures in the composition range 0<x<0.16. The evolution of the photoluminescence spectra and the electrical properties of the InxGa1−xN well were monitored as its thickness was increased for a given % InN. Due to compressive stress and possible quantum-size effects, the emission energy from thin InGaN wells is blueshifted relative to thicker wells of a given % InN. The transition from the blueshifted emission of strained InGaN to redshifted emission of relaxed InGaN is also accompanied by dramatic changes in film conductivity and mobility. The thickness at which the onset of relaxation occurs is deemed the critical layer thickness of the InxGa1−xN film.}, number={25}, journal={Applied Physics Letters}, author={Reed, M. J. and El-Masry, N. A. and Parker, C. A. and Roberts, J. C. and Bedair, S. M.}, year={2000}, pages={4121–4123} }
 @article{parker_roberts_bedair_reed_liu_el-masry_1999, title={Determination of the critical layer thickness in the InGaN/GaN heterostructures}, volume={75}, ISSN={["0003-6951"]}, DOI={10.1063/1.125146}, abstractNote={We present an approach to determine the critical layer thickness in the InxGa1−xN/GaN heterostructure based on the observed change in the photoluminescence emission as the InxGa1−xN film thickness increases. From the photoluminescence data, we identify the critical layer thickness as the thickness where a transition occurs from the strained to unstrained condition, which is accompanied by the appearance of deep level emission and a drop in band edge photoluminescence intensity. The optical data that indicate the onset of critical layer thickness, was also confirmed by the changes in InxGa1−xN surface morphology with thickness, and is consistent with x-ray diffraction measurements.}, number={18}, journal={APPLIED PHYSICS LETTERS}, author={Parker, CA and Roberts, JC and Bedair, SM and Reed, MJ and Liu, SX and El-Masry, NA}, year={1999}, month={Nov}, pages={2776–2778} }
 @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{robins_paul_parker_roberts_bedair_piner_el-masry_1999, title={Optical absorption, Raman, and photoluminescence excitation spectroscopy of inhomogeneous InGaN films}, volume={4S1}, DOI={10.1557/s1092578300002490}, abstractNote={InxGa1−xN films with x=0.06 to x=0.49 were characterized by optical transmittance, Raman, and photoluminescence excitation spectroscopies. Previous microstructural characterizations detected phase separation only in films with x>0.2. The transmittance data suggest that compositional inhomogeneity is also present in the lower-x films (x<0.2). Both Raman and photoluminescence excitation spectra show features that correlate with compositional inhomogeneity and phase separation in the films with x>0.2. The composition dependence of the Raman spectra, from x=0.28 to x=0.49, is consistent with an increase in the size of the phase-separated regions with increasing x.}, number={G3.22}, journal={MRS Internet Journal of Nitride Semiconductor Research}, author={Robins, L. H. and Paul, A. J. and Parker, C. A. and Roberts, J. C. and Bedair, S. M. and Piner, E. L. and El-Masry, N. A.}, year={1999} }
 @article{parker_roberts_bedair_reed_liu_el-masry_robins_1999, title={Optical band gap dependence on composition and thickness of InxGa1-xN (0 < x < 0.25) grown on GaN}, volume={75}, ISSN={["1077-3118"]}, DOI={10.1063/1.125079}, abstractNote={Band gap measurements have been carried out in strained and relaxed InxGa1−xN epilayers with x<0.25. Values of x were determined from x-ray diffraction of relaxed films. The lowest energy absorption threshold, measured by transmittance, was found to occur at the same energy as the peak of the photoluminescence spectrum. Bowing parameters for both strained and relaxed films were determined to be 3.42 and 4.11 eV, respectively. The dependence of the band gap shift, ΔEg, on strain is presented.}, number={17}, journal={APPLIED PHYSICS LETTERS}, author={Parker, CA and Roberts, JC and Bedair, SM and Reed, MJ and Liu, SX and El-Masry, NA and Robins, LH}, year={1999}, month={Oct}, pages={2566–2568} }
 @article{joshkin_parker_bedair_krasnobaev_cuomo_davis_suvkhanov_1998, title={Fine structure of near-band-edge photoluminescence in He+-irradiated GaN grown on SiC}, volume={72}, ISSN={["0003-6951"]}, DOI={10.1063/1.121474}, abstractNote={The effect of He ion implantation on the optical properties of epitaxial GaN-on-SiC was studied. We observed that He+ irradiation increases the relative intensity of the “blue emission” and resistivity of GaN films and decreases the intensity of the near-band-edge photoluminescence. Because the intensity of the main peak is drastically decreased, the fine structure of the near-band-edge photoluminescence in GaN after He+ irradiation was observed. From a comparison of observed sharp lines with photoluminescence peaks of GaN doped with oxygen, we conclude that oxygen can produce a complex, which is characterized by a strong localization of free carriers and a large lattice distortion. The zero-phonon line of this defect has energy close to the band-gap energy of GaN.}, number={22}, journal={APPLIED PHYSICS LETTERS}, author={Joshkin, VA and Parker, CA and Bedair, SM and Krasnobaev, LY and Cuomo, JJ and Davis, RF and Suvkhanov, A}, year={1998}, month={Jun}, pages={2838–2840} }