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通过金属有机化学气相沉积(MOCVD)法,在氢化物气相外延(HVPE)自支撑GaN衬底和蓝宝石(0001)衬底上外延生长AlGaN/AlN/GaN结构的高电子迁移率晶体管(HEMT)材料,采用低压化学气相沉积SiNx作为栅介质层,形成金属绝缘半导体高电子迁移率晶体管(MISHEMT)结构,对比研究了两种器件的材料性能和电学特性.阴极发光测试表明HVPE的自支撑GaN衬底缺陷密度可降至6×105 cm-2量级.自支撑GaN衬底上AlGaN/GaN HEMT结构具有良好的表面形貌,其表面粗糙度Ra仅为0.51 nm,具有较大的源漏电极饱和电流IDS=378 mA/mm和较高跨导Gm=47 mS/mm.动态导通电阻测试进一步表明,自支撑GaN衬底上同质外延生长的GaN缓冲层具有低缺陷密度,使AlGaN/GaN MISHEMT电流崩塌特性得到抑制.“,”By the metal organic chemical vapor deposition (MOCVD) method,an AlGaN/GaN structure of high electron mobility transistors (HEMTs) was grown on free-standing GaN and sapphire (0001) substrates by hydride vapor phase epitaxy (HVPE).With SiNx grown by the low pressure chemical vapor deposition as gate dielectric layer,the metal-insulator semiconductor high electron mobility transistor (MISHEMT) structure was prepared.The material and electri cal properties of two kinds of the devices were compared.The cathodoluminescence test result shows that the defect density of the HVPE free-standing GaN substrate can reduce to 6 × 10s cm-2.The AlGaN/GaN HEMT structure grown on the free-standing GaN substrate has a smooth surface morphology with a surface roughness Ra of 0.51 nm,large saturation current of source and drain electrode of Im=378 mA/mm and large transconductance Gm =47 mS/mm.The dynamic on-resistance measurements result indicates that the homoepitaxy GaN buffer layer on the free-standing GaN substrate has low defect density,and then the current collapse characteristic of the AlGaN/GaN MISHEMT is suppressed.