@article{frajtag_nepal_paskova_bedair_el-masry_2013, title={Multifacet semipolar formation by controlling the groove depth via lateral sidewall epitaxy}, volume={367}, ISSN={["1873-5002"]}, DOI={10.1016/j.jcrysgro.2012.12.039}, abstractNote={We demonstrate InxGa1−xN/GaN light emitting diode structures with different sets of multifacet semipolar formation grown laterally on m-plane sidewalls formed by stripe patterning on preliminary grown c-plane GaN template. It was found that regrowth on shallow side walls within the GaN template resulted in a single semipolar (11¯01) facet, while deeper side walls led to multifacet semipolar formation. Very deep etching through the entire GaN template reaching the underlying sapphire substrates resulted in a combination of semipolar (11¯01) and nonpolar (11¯00) facets. The results indicate that the depth of the groove patterning can be used as a tool for controlling the set of semipolar facet formation. In addition, the growth rate in different crystallographic directions was studied and possible factors affecting the growth rates are discussed.}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Frajtag, P. and Nepal, N. and Paskova, T. and Bedair, S. M. and El-Masry, N. A.}, year={2013}, month={Mar}, pages={88–93} }
 @article{frajtag_el-masry_nepal_bedair_2011, title={Embedded voids approach for low defect density in epitaxial GaN films}, volume={98}, ISSN={["1077-3118"]}, DOI={10.1063/1.3540680}, abstractNote={We have developed a technique for defect reduction in GaN epitaxial films grown on sapphire substrates. This technique relies on the generation of high densities of embedded microvoids (∼108/cm2), a few microns long and less than a micron in diameter. These voids are located near the sapphire substrate, where high densities of dislocations are present. Network of embedded voids offer free surfaces that act as dislocation sinks or termination sites for the dislocations generated at the GaN/sapphire interface. Both transmission electron and atomic force microscopy results confirm the uniform reduction of the dislocation density by two orders of magnitude.}, number={2}, journal={APPLIED PHYSICS LETTERS}, author={Frajtag, P. and El-Masry, N. A. and Nepal, N. and Bedair, S. M.}, year={2011}, month={Jan} }
 @article{frajtag_samberg_el-masry_nepal_bedair_2011, title={Embedded voids formation by overgrowth on GaN nanowires for high-quality GaN films}, volume={322}, ISSN={["0022-0248"]}, DOI={10.1016/j.jcrysgro.2011.02.032}, abstractNote={We report on the epitaxial growth of GaN films on GaN nanowires. GaN nanowires were prepared by the mask-less dry etching technique. The etched, then annealed nanowires form semi-polar and non-polar plane facets with hexagonal symmetry. The different growth rates on the different plane facets result in the formation of void networks. These networks of embedded voids are located near the sapphire substrate, where a high density of dislocations is present. The voids, a few microns in length and a fraction of a micron in diameter, offer free surfaces for dislocation termination, enabling the embedded void approach (EVA) to reduce dislocations. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) studies show uniform reduction of the dislocation density over large area substrates by about three orders of magnitude and lower surface roughness than the GaN starting material.}, number={1}, journal={JOURNAL OF CRYSTAL GROWTH}, author={Frajtag, P. and Samberg, J. P. and El-Masry, N. A. and Nepal, N. and Bedair, S. M.}, year={2011}, month={May}, pages={27–32} }
 @article{woodward_nepal_mitchell_feng_li_jiang_lin_zavada_dierolf_2011, title={Enhanced magnetization in erbium doped GaN thin films due to strain induced electric fields}, volume={99}, number={12}, journal={Applied Physics Letters}, author={Woodward, N. T. and Nepal, N. and Mitchell, B. and Feng, I. W. and Li, J. and Jiang, H. X. and Lin, J. Y. and Zavada, J. M. and Dierolf, V.}, year={2011} }
 @article{nepal_frajtag_zavada_el-masry_bedair_wetzel_khan_2011, title={Light emitting diodes based on sidewall m-plane epitaxy of etched GaN/sapphire templates}, volume={8}, ISSN={["1862-6351"]}, DOI={10.1002/pssc.201000983}, abstractNote={Abstract}, number={7-8}, journal={PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 8, NO 7-8}, author={Nepal, N. and Frajtag, P. and Zavada, J. M. and El-Masry, N. A. and Bedair, S. M. and Wetzel, C and Khan, A}, year={2011} }
 @article{wang_steckl_nepal_zavada_2010, title={Electrical and magnetic properties of GaN codoped with Eu and Si}, volume={107}, number={1}, journal={Journal of Applied Physics}, author={Wang, R. and Steckl, A. J. and Nepal, N. and Zavada, J. M.}, year={2010} }
 @inproceedings{luen_nepal_frajtag_zavada_brown_hommerich_bedair_el masry_2010, title={Ferromagnetism and near infrared luminescence in neodymium and erbium doped gallium nitride via diffusion}, volume={1183}, DOI={10.1557/proc-1183-ff06-01}, abstractNote={Abstract}, booktitle={Novel materials and devices for spintronics}, author={Luen, M. O. and Nepal, N. and Frajtag, P. and Zavada, J. M. and Brown, E. and Hommerich, U. and Bedair, S. M. and El Masry, N. A.}, year={2010}, pages={45–50} }
 @article{nepal_luen_zavada_bedair_frajtag_el-masry_2009, title={Electric field control of room temperature ferromagnetism in III-N dilute magnetic semiconductor films}, volume={94}, ISSN={["1077-3118"]}, DOI={10.1063/1.3110963}, abstractNote={We report on the electrical field control of ferromagnetism (FM) at room temperature in III-N dilute magnetic semiconductor (DMS) films. A GaMnN layer was grown on top of an n-GaN substrate and found to be almost always paramagnetic. However, when grown on a p-type GaN layer, a strong saturation magnetization (Ms) was observed. This FM in GaMnN can be controlled by depletion of the holes in the GaMnN/p-GaN/n-GaN multilayer structures. We have demonstrated the dependence of the FM on the thickness of the p-GaN in this heterostructure and on the applied bias to the GaN p-n junction. The Ms was measured by an alternating gradient magnetometer (AGM) and a strong correlation between the hole concentration near the GaMnN/p-GaN interface and the magnetic properties of the DMS was observed. At room temperature an anomalous Hall effect was measured for zero bias and an ordinary Hall effect for reverse bias in a fully depleted p-GaN layer. This is in close agreement with the AGM measurement results.}, number={13}, journal={APPLIED PHYSICS LETTERS}, author={Nepal, N. and Luen, M. Oliver and Zavada, J. M. and Bedair, S. M. and Frajtag, P. and El-Masry, N. A.}, year={2009}, month={Mar} }
 @article{nepal_zavada_dahal_ugolini_sedhain_lin_jiang_2009, title={Optical enhancement of room temperature ferromagnetism in Er-doped GaN epilayers}, volume={95}, number={2}, journal={Applied Physics Letters}, author={Nepal, N. and Zavada, J. M. and Dahal, R. and Ugolini, C. and Sedhain, A. and Lin, J. Y. and Jiang, H. X.}, year={2009} }