Properties of Si Doped Al0.4Ga0.6N Epilayers with Different AlGaN Window Layer Grown on High Quality AlN Buffer by MOCVD
YU Chen-Hui1,2, LIU Cheng1, HAN Xiang-Yun1, KANG Wei1, FANG Yan-Yan1, DAI Jiang-Nan1,2, WU Zhi-Hao1, CHEN Chang-Qing1**
1Wuhan National Laboratory for Optoelectronics, College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 2National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083
Properties of Si Doped Al0.4Ga0.6N Epilayers with Different AlGaN Window Layer Grown on High Quality AlN Buffer by MOCVD
YU Chen-Hui1,2, LIU Cheng1, HAN Xiang-Yun1, KANG Wei1, FANG Yan-Yan1, DAI Jiang-Nan1,2, WU Zhi-Hao1, CHEN Chang-Qing1**
1Wuhan National Laboratory for Optoelectronics, College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 2National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083
摘要Si-doped Al0.4Ga0.6N (Si−Al0.4Ga0.6N) epilayers grown on an AlGaN window layer (WL) with different Al contents are prepared using a high−quality AlN buffer layer by metal-organic chemical vapor deposition. Surface morphology, crystalline quality and electric properties of these epilayers are investigated by using atomic force microscopy, x-ray diffraction, Raman scattering spectrum and Hall techniques. Results show that the surface morphology of these epilayers are mainly determined by the Si-doping level which, together with the effect of Al content of WL, also has an obvious impact on the electron concentrations. On the other hand, the insertion of AlGaN WL is helpful to the increase of Si doping level and conductivity of subsequently grown Si-Al0.4Ga0.6N epilayers. However, the insertion as well as the increase of Al content of WL result in increase of dislocation densities, compressive strain in Si−Al0.4Ga0.6N epilayers, and tilt of AlN subgrains at the top interface of the buffer layer. Further, the degradation of crystalline quality with the Al content of WL exerts a decisive influence on the conductivity of the Si−Al0.4Ga0.6N epilayers grown on WL with Al content of 0.6 through a dramatic decrease in electron mobility.
Abstract：Si-doped Al0.4Ga0.6N (Si−Al0.4Ga0.6N) epilayers grown on an AlGaN window layer (WL) with different Al contents are prepared using a high−quality AlN buffer layer by metal-organic chemical vapor deposition. Surface morphology, crystalline quality and electric properties of these epilayers are investigated by using atomic force microscopy, x-ray diffraction, Raman scattering spectrum and Hall techniques. Results show that the surface morphology of these epilayers are mainly determined by the Si-doping level which, together with the effect of Al content of WL, also has an obvious impact on the electron concentrations. On the other hand, the insertion of AlGaN WL is helpful to the increase of Si doping level and conductivity of subsequently grown Si-Al0.4Ga0.6N epilayers. However, the insertion as well as the increase of Al content of WL result in increase of dislocation densities, compressive strain in Si−Al0.4Ga0.6N epilayers, and tilt of AlN subgrains at the top interface of the buffer layer. Further, the degradation of crystalline quality with the Al content of WL exerts a decisive influence on the conductivity of the Si−Al0.4Ga0.6N epilayers grown on WL with Al content of 0.6 through a dramatic decrease in electron mobility.
YU Chen-Hui;LIU Cheng;HAN Xiang-Yun;KANG Wei;FANG Yan-Yan;DAI Jiang-Nan;WU Zhi-Hao;CHEN Chang-Qing**
. Properties of Si Doped Al0.4Ga0.6N Epilayers with Different AlGaN Window Layer Grown on High Quality AlN Buffer by MOCVD[J]. 中国物理快报, 2011, 28(2): 27301-027301.
YU Chen-Hui, LIU Cheng, HAN Xiang-Yun, KANG Wei, FANG Yan-Yan, DAI Jiang-Nan, WU Zhi-Hao, CHEN Chang-Qing**
. Properties of Si Doped Al0.4Ga0.6N Epilayers with Different AlGaN Window Layer Grown on High Quality AlN Buffer by MOCVD. Chin. Phys. Lett., 2011, 28(2): 27301-027301.
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