Publication Date:
2016-04-12
Description:
Among the major obstacles for development of non-polar and semipolar GaN structures on foreign substrates are stacking faults which deteriorate the structural and optical quality of the material. In this work, an in-situ SiN x nano-network has been employed to achieve high quality heteroepitaxial semipolar ( 11 2 ¯ 2 ) GaN on m-plane sapphire with reduced stacking fault density. This approach involves in-situ deposition of a porous SiN x interlayer on GaN that serves as a nano-mask for the subsequent growth, which starts in the nanometer-sized pores (window regions) and then progresses laterally as well, as in the case of conventional epitaxial lateral overgrowth (ELO). The inserted SiN x nano-mask effectively prevents the propagation of defects, such as dislocations and stacking faults, in the growth direction and thus reduces their density in the overgrown layers. The resulting semipolar ( 11 2 ¯ 2 ) GaN layers exhibit relatively smooth surface morphology and improved optical properties (PL intensity enhanced by a factor of 5 and carrier lifetimes by 35% to 85% compared to the reference semipolar ( 11 2 ¯ 2 ) GaN layer) which approach to those of the c -plane in-situ nano-ELO GaN reference and, therefore, holds promise for light emitting and detecting devices.
Print ISSN:
0021-8979
Electronic ISSN:
1089-7550
Topics:
Physics