Effect of thickness on the microstructure of GaN films on Al_2 O_3 (0001) by laser molecular beam epitaxy  

作　　者：刘莹莹 朱俊 罗文博 郝兰众 张鹰 李言荣 

机构地区：[1]State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China

出　　处：《Chinese Physics B》2011年第10期435-441,共7页中国物理B（英文版）

基　　金：supported by the Major State Basic Research Development Program of China (Grant No. 61363);the National Natural Science Foundation of China (Grant Nos. 50772019 and 61021061)

摘　　要：Heteroepitaxial GaN films are grown on sapphire （0001） substrates using laser molecular beam epitaxy. The growth processes are in-situ monitored by reflection high energy electron diffraction. It is revealed that the growth mode of GaN transformed from three-dimensional （3D） island mode to two-dimensional （2D） layer-by-layer mode with the increase of thickness. This paper investigates the interfacial strain relaxation of GaN films by analysing their diffraction patterns. Calculation shows that the strain is completely relaxed when the thickness reaches 15 nm. The surface morphology evolution indicates that island merging and reduction of the island-edge barrier provide an effective way to make GaN films follow a 2D layer-by-layer growth mode. The ll0-nm GaN films with a 2D growth mode have smooth regular hexagonal shapes. The X-ray diffraction indicates that thickness has a significant effect on the crystallized quality of GaN thin films.Heteroepitaxial GaN films are grown on sapphire （0001） substrates using laser molecular beam epitaxy. The growth processes are in-situ monitored by reflection high energy electron diffraction. It is revealed that the growth mode of GaN transformed from three-dimensional （3D） island mode to two-dimensional （2D） layer-by-layer mode with the increase of thickness. This paper investigates the interfacial strain relaxation of GaN films by analysing their diffraction patterns. Calculation shows that the strain is completely relaxed when the thickness reaches 15 nm. The surface morphology evolution indicates that island merging and reduction of the island-edge barrier provide an effective way to make GaN films follow a 2D layer-by-layer growth mode. The ll0-nm GaN films with a 2D growth mode have smooth regular hexagonal shapes. The X-ray diffraction indicates that thickness has a significant effect on the crystallized quality of GaN thin films.

关 键 词：reflection high energy electron diffraction thin films laser molecular beam epitaxy GaN sapphires 

分 类 号：O484.1[理学—固体物理] TN304.23[理学—物理]