@article{you_liu_jiang_wang_el-masry_hosalli_bedair_xu_2014, title={Enhanced radiative recombination and suppressed Auger process in semipolar and nonpolar InGaN/GaN quantum wells grown over GaN nanowires}, volume={39}, ISSN={["1539-4794"]}, DOI={10.1364/ol.39.001501}, abstractNote={The mechanism behind the improved light emission properties of semipolar and nonpolar InGaN/GaN multiple quantum wells (MQWs) conformally grown over n-GaN nanowires (NWs) was studied using variable-temperature photoluminescence and time-resolved photoluminescence (TRPL). A reduced internal polarization electric field was found to account for the observed enhancement in the radiative recombination rate and internal quantum efficiency of the MQWs on NWs. Additionally, the excitation-dependent TRPL results indicate a significantly depressed Auger recombination in MQWs grown on NWs that can be attributed to the feature of ultralow dislocation density of the MQWs grown over GaN nanostructures.}, number={6}, journal={OPTICS LETTERS}, author={You, Guanjun and Liu, Jie and Jiang, Zhenyu and Wang, Li and El-Masry, N. A. and Hosalli, A. M. and Bedair, Salah M. and Xu, Jian}, year={2014}, month={Mar}, pages={1501–1504} }
 @article{broeck_bharrat_hosalli_el-masry_bedair_2014, title={Strain-balanced InGaN/GaN multiple quantum wells}, volume={105}, ISSN={["1077-3118"]}, DOI={10.1063/1.4890738}, abstractNote={InGaN/GaN multiple quantum well (MQW) structures suffer from a high amount of compressive strain in the InGaN wells and the accompanied piezoelectric field resulting in both a blue shift in emission and a reduction of emission intensity. We report the growth of InxGa1−xN/GaN “strain-balanced” multiple quantum wells (SBMQWs) grown on thick InyGa1−yN templates for x > y by metal organic chemical vapor deposition. SBMQWs consist of alternating layers of InxGa1−xN wells and GaN barriers under compressive and tensile stress, respectively, which have been lattice matched to a thick InyGa1−yN template. Growth of the InyGa1−yN template is also detailed in order to achieve thick, relaxed InyGa1−yN grown on GaN without the presence of V-grooves. When compared to conventional InxGa1−xN/GaN MQWs grown on GaN, the SBMQW structures exhibit longer wavelength emission and higher emission intensity for the same InN mole fraction due to a reduction in the well strain and piezoelectric field. By matching the average lattice constant of the MQW active region to the lattice constant of the InyGa1−yN template, essentially an infinite number of periods can be grown using the SBMQW growth method without relaxation-related effects. SBMQWs can be utilized to achieve longer wavelength emission in light emitting diodes without the use of excess indium and can be advantageous in addressing the “green gap.”}, number={3}, journal={APPLIED PHYSICS LETTERS}, author={Broeck, D. M. and Bharrat, D. and Hosalli, A. M. and El-Masry, N. A. and Bedair, S. M.}, year={2014}, month={Jul} }
 @article{bharrat_hosalli_van den broeck_samberg_bedair_el-masry_2013, title={Gallium nitride nanowires by maskless hot phosphoric wet etching}, volume={103}, ISSN={["1077-3118"]}, DOI={10.1063/1.4819272}, abstractNote={We demonstrate gallium nitride (GaN) nanowires formation by controlling the selective and anisotropic etching of N-polar GaN in hot phosphoric acid. Nanowires of ∼109/cm,2 total height of ∼400 nm, and diameters of 170–200 nm were obtained. These nanowires have both non-polar {11¯00}/ {112¯0} and semi-polar {1011¯} facets. X–Ray Diffraction characterization shows that screw dislocations are primarily responsible for preferential etching to create nanowires. Indium gallium nitride multi-quantum wells (MQWs) grown on these GaN nanowires showed a blue shift in peak emission wavelength of photoluminescence spectra, and full width at half maximum decreased relative to MQWs grown on planar N-polar GaN, respectively.}, number={8}, journal={APPLIED PHYSICS LETTERS}, author={Bharrat, D. and Hosalli, A. M. and Van Den Broeck, D. M. and Samberg, J. P. and Bedair, S. M. and El-Masry, N. A.}, year={2013}, month={Aug} }
 @article{hosalli_van den broeck_bharrat_el-masry_bedair_2013, title={Inversion by metalorganic chemical vapor deposition from N- to Ga-polar gallium nitride and its application to multiple quantum well light-emitting diodes}, volume={103}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.4841755}, DOI={10.1063/1.4841755}, abstractNote={We demonstrate a metalorganic chemical vapor deposition growth approach for inverting N-polar to Ga-polar GaN by using a thin inversion layer grown with high Mg flux. The introduction of this inversion layer allowed us to grow p-GaN films on N-polar GaN thin film. We have studied the dependence of hole concentration, surface morphology, and degree of polarity inversion for the inverted Ga-polar surface on the thickness of the inversion layer. We then use this approach to grow a light emitting diode structure which has the MQW active region grown on the advantageous N-polar surface and the p-layer grown on the inverted Ga-polar surface.}, number={23}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Hosalli, A. M. and Van Den Broeck, D. M. and Bharrat, D. and El-Masry, N. A. and Bedair, S. M.}, year={2013}, month={Dec}, pages={231108} }
 @article{roberts_mohanta_everitt_leach_broeck_hosalli_paskova_bedair_2013, title={Spectroscopic investigation of coupling among asymmetric InGaN/GaN multiple quantum wells grown on non-polar a-plane GaN substrates}, volume={103}, ISSN={["1077-3118"]}, DOI={10.1063/1.4827536}, abstractNote={Low defect density asymmetric multiple quantum wells (MQWs) of InGaN/GaN grown on non-polar a-plane GaN substrates were investigated using time-integrated and time-resolved photoluminescence spectroscopy. Comparison of these spectra with the predicted emission energies reveals that these QWs may be spectrally resolved at low temperatures. However, a combination of thermal activation and resonant tunneling of carriers increasingly coupled the QWs, favoring emission from the lowest energy QWs with increasing temperature in a manner analogous to MQWs composed of other non-polar semiconductor materials but unlike most InGaN MQWs grown on polar substrates and influenced by the strong polarization-dependent effects.}, number={18}, journal={APPLIED PHYSICS LETTERS}, author={Roberts, A. T. and Mohanta, A. and Everitt, H. O. and Leach, J. H. and Broeck, D. and Hosalli, A. M. and Paskova, T. and Bedair, S. M.}, year={2013}, month={Oct} }