利用混合极性制备多孔缓冲层及其在GaN厚膜外延中的应用

使用分子束外延(MBE)技术在(0001)面蓝宝石衬底上生长混合极性的氮化镓(GaN)薄膜,利用不同极性面的GaN薄膜在强碱溶液中腐蚀特性的差异,混和极性样品经腐蚀处理后,得到了一层具有多孔结构的GaN层.以多孔结构的GaN作为缓冲层,用卤化物气相外延(HVPE)方法生长GaN厚膜.X射线双晶衍射和光致发光等测试结果表明,多孔结构的GaN缓冲层可以有效地释放GaN厚膜和衬底之间因热膨胀系数失配产生的应力,使GaN厚膜晶体的质量得到很大提高.

Growth of Thick GaN Films on Mixed-Polarity Buffer by Halide Vapor Phase Epitaxy

GaN thin films with mixed-polarity were initially grown on (0001) sapphire substrates by molecular beam epitaxy (MBE).The samples were etched by alkali solution,and porous GaN films were formed.GaN thick films were grown on the porous GaN layers by hydride vapor phase epitaxy (HVPE).These HVPE-GaN epilayers were characterized by atomic force microscopy,X-ray diffraction,and photoluminescence spectroscopy.The results indicate that the crystalline quality of HVPE-GaN is improved by using the porous GaN buffer,as the stress is reduced markedly.