Dechao Yang

Improvement of quality and strain relaxation of GaN epilayer grown on SiC substrate by in situ SiNx interlayer

Improved structural quality and tensile stress releasing were realized in GaN thin films grown on 6H–SiC by metal organic chemical vapor deposition using an in situ porous SiNx interlayer. The SiNx was formed in situ in the growth chamber by simultaneous flow of diluted silane and ammonia, leading to the formation of a randomly distributed mask layer and induced lateral overgrowth similar to conventional epitaxial lateral overgrowth of GaN. The full width at half maximum (FWHM) of X-ray diffraction peaks decreases dramatically by the SiNx interlayer, indicating an improved crystalline quality. Also, it was found that the biaxial tensile stress in the GaN film was significantly reduced by in situ SiNx interlayer from Raman spectra. Low temperature photoluminescence spectra exhibited a narrower FWHM by the SiNx interlayer.

Improvement of the quality of GaN epilayer by combining a SiNx interlayer and changed GaN growth mode

GaN epilayers with porous SiNx interlayer and changed growth modes were grown by metal–organic chemical vapor deposition on c-plane sapphire substrates. Comparing with GaN epilayer grown by ordinary method, the crystalline qualities were significantly improved. The improvement was attributed to the reduction of the density of threading dislocations causing by over-growth process combining with delayed coalescence of individual GaN islands. The influence of the deposition and annealing of nucleation layer on the GaN regrowth was also discussed.

Improved quality of GaN epilayer grown on porous SiC substrate by in situ H2 pre-treatment

GaN epilayers were grown on the Si-terminated (0001) 6H-SiC substrates pre-treated by in situ H2 in metal organic chemical vapor deposition system. It was found that in situ H2 treatment brought a porous SiC surface. The influence of H2 pre-treatment conditions on SiC surface was carefully investigated. Moreover, our experiment demonstrated that the H2 pre-treatment can distinctly influence the GaN basic characteristics.

Dominant UV emission from p-MgZnO/n-GaN light emitting diodes

The authors report on the fabrication of p-Mg0.1Zn0.9O/n-GaN light emitting diodes (LEDs). Under forward bias, dominant ultraviolet (UV) electroluminescence is detected within 360-380 nm caused by near band edge (NBE) radiative recombination from both n-GaN and p-Mg0.1Zn0.9O. It is worth noting that the intensity ratio of UV-NBE/visible-DLE reaches up to 50, which indicates the potential applications of this structure in the short wavelength LEDs.

Improving the quality of GaN epilayer by preparing a novel patterned sapphire substrate

Abstract GaN epilayer was grown on a new polyhedral patterned sapphire substrate (new PSS) by metal–organic chemical vapor deposition. The new PSS was prepared by combining the dry etching technique and wet etching technique. The X-ray diffraction indicated that the full width at half maximum values of (0002) and (

Selective Growth of GaN on Slope Cone-shaped Patterned Sapphire Substrate

10\overline{1}2

Evolution of the crystallographic planes of cone-shaped patterned sapphire substrate treated by wet etching

101¯2) diffraction peaks in the GaN epilayer grown on the new PSS were evidently smaller than that in the GaN epilayer grown on the normal treated PSS. The improvement of GaN quality was attributed to the reduction of threading dislocations (TDs) in GaN epilayer, and the mechanism of the reduction of TDs was analyzed. The influence of the new PSS on the optical properties as well as the residual stress in GaN epilayer was also discussed.

Smooth surface morphology and low dislocation density of p-GaN using indium-assisted growth

GaN epilayers with a porous SiNx interlayer were grown by metal-organic chemical vapor deposition on c-plane sapphire substrates. It is found that the crystalline qualities are significantly improved with SiNx growth. The improvement is attributed to the reduction of the density of threading dislocations (TDs) by an over-growth process of GaN grown on a SiNx interlayer. The influence mechanism of SiNx interlayers on GaN growth mode is also discussed.