Effect of thickness on the microstructure of GaN films on Al 2 O 3 (0001) by laser molecular beam epitaxy
Effect of thickness on the microstructure of GaN films on Al 2 O 3 (0001) by laser molecular beam epitaxy
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DOI：
10.1088/1674-1056/20/10/108102
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发表时间：
2011-10
影响因子：
1.7
通讯作者：
Liu Ying-ying;Zhu Jun;Luo Wenbo;Hao Lanzhong;Z. Ying;Li Yanrong
中科院分区：
文献类型：
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作者：
Liu Ying-ying;Zhu Jun;Luo Wenbo;Hao Lanzhong;Z. Ying;Li Yanrong
采用激光分子束外延技术在蓝宝石（0001）衬底上生长了异质外延GaN薄膜。生长过程中原位监测反射高能电子衍射。结果表明，随着厚度的增加，GaN的生长模式由三维岛状模式向二维层-层模式转变。本文通过分析GaN薄膜的衍射花样，研究了GaN薄膜的界面应变弛豫。计算表明，当厚度达到15 nm时，应变完全弛豫。表面形貌的演变表明，岛合并和岛边缘势垒的减少提供了一个有效的方法，使GaN薄膜遵循二维逐层生长模式。具有2D生长模式的110-nm GaN薄膜具有光滑的规则六边形形状。X射线衍射分析表明，厚度对GaN薄膜的结晶质量有显著影响。
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 110-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.