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研究了直接在 Zn Al2 O4/α-Al2 O3 衬底上用 MOCVD法一步生长 Ga N薄膜 .利用脉冲激光淀积法在α-Al2 O3衬底上淀积了高质量 Zn O薄膜 ,对 Zn O/α-Al2 O3 样品在 110 0℃退火得到了具有 Zn Al2 O4覆盖层的 α-Al2 O3 衬底 ,并在此复合衬底上利用光加热低压 MOCVD法直接生长了纤锌矿结构 Ga N. X射线衍射谱表明反应得到的Zn Al2 O4层为 ( 111)取向 .扫描电子显微镜照片显示随退火时间从小于 3 0 min增加到 2 0 h,Zn Al2 O4表面由均匀的岛状结构衍变为突起的线状结构 ,相应的 Ga N X射线衍射谱表明 Ga N由 c轴单晶变为多晶 ,单晶 Ga N的摇摆曲线半高宽为 0 .4°.结果表明薄 Zn Al2 O4覆盖层的岛状结构有利于 Ga N生长初期的成核 ,从而提高了 Ga N的晶体质量
The growth of GaN thin films directly on the Zn Al2 O4 / α-Al2 O3 substrate by MOCVD was studied.The high quality Zn O thin films were deposited on the α-Al2 O3 substrate by pulsed laser deposition, / α-Al 2 O 3 samples were annealed at 110 0 C to obtain α-Al 2 O 3 substrates with Zn Al 2 O 4 cladding layer, and GaN was directly grown on the composite substrate by light-heating low pressure MOCVD. X-ray diffraction (XRD) spectra showed that the Zn Al 2 O 4 layer was (111) oriented, and the scanning electron microscopy (SEM) images showed that the surface of Zn Al 2 O 4 was changed from uniform island structure to protuberance as the annealing time increased from less than 30 min to 20 h The corresponding Ga NX ray diffraction spectrum shows that Ga N is changed from c-axis single crystal to polycrystalline and the FWHM of the single-crystal Ga N is 0.4 °. The results show that the thin Zn Al 2 O 4 overlay Island structure is conducive to the early growth of Ga N nucleation, thereby increasing the crystal quality Ga N