Synthesis of ZnAl_2O_4/α-Al_2O_3 complex substrates and growth of GaN films  

作　　者：毕朝霞 张荣 李卫平 王栩生 顾书林 沈波 施毅 刘治国 郑有炓 

机构地区：[1]National Laboratory of Solid State Microstructures and Department of Physics,Nanjing University,Nanjing 210093,China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2003年第1期41-46,共6页中国科学：物理学、力学、天文学（英文版）

基　　金：Special Funds for Major State Basic Research Projects of China(Grant No.#G20000683);Distinguished Young Scientist Grant of China (Grant No.60025411);the National Natural Science Foundation of China(Grant Nos.69806006,69976014,69636010 and 69987001);the National High Technology Research & Development Project of China

摘　　要：With the solid phase reaction between pulsed-laser-deposited (PLD) ZnOfilm and α-Al2O3 substrate, ZnAl2O4/α-Al2O3 complex substrates were synthesized. X-ray diffraction (XRD) spectra show that as the reaction proceeds, ZnAl2O4 changes from the initial (111)-oriented single crystal to poly-crystal, and then to inadequate (111) orientation. Corresponding scanning electron microscope (SEM)images indicate that the surface morphology of ZnAl2O4 transforms from uniform islands to stick structures, and then to bulgy-line structures. In addition, XRDspectra present that ZnAl2O4 prepared at low temperature is unstable at the environment of higher temperature. On the as-obtained ZnAl2O4/α-Al2O3 substrates, GaN films were grown without any nitride buffer using light-radiation heating low-pressure MOCVD (LRH-LP-MOCVD). XRD spectra indicate that GaN film on this kind of complex substrate changes from c-axis single crystal to poly-crystal as ZnAl2O4 layer is thickened. For the single crystal GaN, its full width at half maximum (FWHM) of X-ray rocking curve is 0.4°. Results indicate that islands on thin ZnAl2O4 layer can promote nucleation at initial stage of GaN growth, which leadsto the (0001)-oriented GaN film.With the solid phase reaction between pulsed-laser-deposited (PLD) ZnO film and α-Al2O3 substrate, ZnAl2O4/α-Al2O3 complex substrates were synthesized. X-ray diffraction (XRD) spectra show that as the reaction proceeds, ZnAl2O4 changes from the initial (111)-oriented single crystal to poly-crystal, and then to inadequate (111) orientation. Corresponding scanning electron microscope (SEM) images indicate that the surface morphology of ZnAl2O4 transforms from uniform islands to stick structures, and then to bulgy-line structures. In addition, XRD spectra present that ZnAl2O4 prepared at low temperature is unstable at the environment of higher temperature. On the as-obtained ZnAl2O4/α-Al2O3 substrates, GaN films were grown without any nitride buffer using light-radiation heating low-pressure MOCVD (LRH-LP-MOCVD). XRD spectra indicate that GaN film on this kind of complex substrate changes fromc-axis single crystal to poly-crystal as ZnAl2O4 layer is thickened. For the single crystal GaN, its full width at half maximum (FWHM) of X-ray rocking curve is 0.4°. Results indicate that islands on thin ZnAl2O4 layer can promote nucleation at initial stage of GaN growth, which leads to the (0001)-oriented GaN film.

关 键 词：GaN  ZnAl2O4  MOCVD  X-ray diffraction  SCANNING electron microscope. 

分 类 号：O484[理学—固体物理]