Nucleation of GaN on sapphire substrates at intermediate temperatures by Hydride Vapor Phase Epitaxy
Nucleation of GaN on sapphire substrates at intermediate temperatures by Hydride Vapor Phase Epitaxy
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DOI：
10.1002/crat.201100461
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发表时间：
2012-02
影响因子：
1.5
通讯作者：
G. Lukin;C. Röder;E. Niederschlag;Y. Shashev;U. Mühle;O. Pätzold;J. Kortus;D. Rafaja;M. Stelter
中科院分区：
文献类型：
--
作者：
G. Lukin;C. Röder;E. Niederschlag;Y. Shashev;U. Mühle;O. Pätzold;J. Kortus;D. Rafaja;M. Stelter
提出了一种利用氢化物气相外延直接在蓝宝石衬底上沉积氮化镓层的新方法。两步沉积过程包括在750 - 900°C的中间温度下生长GaN成核层，随后在约1040°C的高温下过度生长。制备了厚度达2 μm的封闭和非封闭成核层，并通过扫描电镜、透射电镜、微拉曼光谱和X射线衍射对其进行了表征。对于成核岛的密度和大小分布而言，780℃的生长温度是最佳的。在成核层上进行的拉曼测量显示，残余应力几乎为零，表明从生长温度冷却时有效的应力松弛。第一次过度生长实验的结果表明，在成核层上生长出10 μm厚、无裂纹、高结晶质量的GaN层是可能的。（©2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim）
A novel approach to deposit GaN layers directly on a sapphire substrate by Hydride Vapor Phase Epitaxy is presented. The two‐step deposition process includes the growth of GaN nucleation layers at intermediate temperatures in the range of 750 – 900 °C and subsequent high‐temperature overgrowth at about 1040 °C. Closed and non‐closed nucleation layers with a thickness of up to 2 μm were produced and characterized by scanning and transmission electron microscopy, micro‐Raman spectroscopy and X‐ray diffraction. A growth temperature of 780 °C is found to be optimal with respect to density and size distribution of nucleation islands. Raman measurements performed on the nucleation layers reveal nearly zero residual stress indicating effective stress relaxation on cooling down from growth temperature. The results of first overgrowth experiments demonstrate the possibility to grow 10 μm thick, crack‐free GaN layers of high crystalline quality on the nucleation layers. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)