在氢化物气相外延 (HVPE)生长 Ga N过程中 ,发现了一种在成核阶段向生长区添加额外 HCl来改善 Ga N外延薄膜质量的方法 ,并且讨论了额外 HCl和氮化对 Ga N形貌和质量的影响 .两种方法都可以大幅度地改善 Ga N的晶体质量和性质 ,但机理不...在氢化物气相外延 (HVPE)生长 Ga N过程中 ,发现了一种在成核阶段向生长区添加额外 HCl来改善 Ga N外延薄膜质量的方法 ,并且讨论了额外 HCl和氮化对 Ga N形貌和质量的影响 .两种方法都可以大幅度地改善 Ga N的晶体质量和性质 ,但机理不同 .氮化是通过在衬底表面形成 Al N小岛 ,促进了衬底表面的成核和薄膜的融合 ;而添加额外展开更多
Thick GaN films were grown on GaN/sapphire template in a vertical HVPE reactor. Various material characterization techniques,including AFM, SEM, XRD, RBS/Channeling, CL, PL, and XPS, were used to characterize these Ga...Thick GaN films were grown on GaN/sapphire template in a vertical HVPE reactor. Various material characterization techniques,including AFM, SEM, XRD, RBS/Channeling, CL, PL, and XPS, were used to characterize these GaN epitaxial films. It was found that stepped/terraced structures appeared on the film surface,which were indicative of a nearly step-flow mode of growth for the HVPE GaN despite the high growth rate. A few hexagonal pits appeared on the surface, which have strong light emission. After being etched in molten KOH, the wavy steps disappeared and hexagonal pits with {1010} facets appeared on the surface. An EPD of only 8 ×10^6cm^-2 shows that the GaN film has few dislocations. Both XRD and RBS channeling indicate the high quality of the GaN thick films. Sharp band-edge emission with a full width at half maximum（FWHM）of 67meV was observed, while the yellow and infrared emissions were also found. These emissions are likely caused by native defects and C and O impurities.展开更多
Effects of in situ annealing on the structural and optical properties of Gallium nitride （GaN） layers grown on （0001） sapphire by hydride vapor phase epitaxy （HVPE） are studied. The properties of GaN epilayers a...Effects of in situ annealing on the structural and optical properties of Gallium nitride （GaN） layers grown on （0001） sapphire by hydride vapor phase epitaxy （HVPE） are studied. The properties of GaN epilayers are improved by insitu annealing at growth temperature under ammonia （NH3） atmosphere. X-ray diffraction （XRD） analysis shows that the full width at half maximum （FWHM） of the rocking curves narrows as the annealing time increases. Raman scattering spectroscopy shows that E2 （high） peak positions shift to the low frequency region. Compared to without annealing and epilayers annealed with bulk GaN,the E2 （high） peak position of epilayers becomes closer to that of bulk GaN as the in situ annealing time increases. The biaxial compressive stress decreases after in situ annealing. Photoluminescence （PL） examination agrees well with XRD and Raman scattering analyses. These results suggest that the optical and structural properties of GaN epilayers can be improved by in situ annealing.展开更多
文摘在氢化物气相外延 (HVPE)生长 Ga N过程中 ,发现了一种在成核阶段向生长区添加额外 HCl来改善 Ga N外延薄膜质量的方法 ,并且讨论了额外 HCl和氮化对 Ga N形貌和质量的影响 .两种方法都可以大幅度地改善 Ga N的晶体质量和性质 ,但机理不同 .氮化是通过在衬底表面形成 Al N小岛 ,促进了衬底表面的成核和薄膜的融合 ;而添加额外
文摘Thick GaN films were grown on GaN/sapphire template in a vertical HVPE reactor. Various material characterization techniques,including AFM, SEM, XRD, RBS/Channeling, CL, PL, and XPS, were used to characterize these GaN epitaxial films. It was found that stepped/terraced structures appeared on the film surface,which were indicative of a nearly step-flow mode of growth for the HVPE GaN despite the high growth rate. A few hexagonal pits appeared on the surface, which have strong light emission. After being etched in molten KOH, the wavy steps disappeared and hexagonal pits with {1010} facets appeared on the surface. An EPD of only 8 ×10^6cm^-2 shows that the GaN film has few dislocations. Both XRD and RBS channeling indicate the high quality of the GaN thick films. Sharp band-edge emission with a full width at half maximum（FWHM）of 67meV was observed, while the yellow and infrared emissions were also found. These emissions are likely caused by native defects and C and O impurities.
文摘Effects of in situ annealing on the structural and optical properties of Gallium nitride （GaN） layers grown on （0001） sapphire by hydride vapor phase epitaxy （HVPE） are studied. The properties of GaN epilayers are improved by insitu annealing at growth temperature under ammonia （NH3） atmosphere. X-ray diffraction （XRD） analysis shows that the full width at half maximum （FWHM） of the rocking curves narrows as the annealing time increases. Raman scattering spectroscopy shows that E2 （high） peak positions shift to the low frequency region. Compared to without annealing and epilayers annealed with bulk GaN,the E2 （high） peak position of epilayers becomes closer to that of bulk GaN as the in situ annealing time increases. The biaxial compressive stress decreases after in situ annealing. Photoluminescence （PL） examination agrees well with XRD and Raman scattering analyses. These results suggest that the optical and structural properties of GaN epilayers can be improved by in situ annealing.
