TEMinvestigation of anisotropic defect structure in cubic GaN/AlGaAs/GaAs(001) grown by MOVPE
TEMinvestigation of anisotropic defect structure in cubic GaN/AlGaAs/GaAs(001) grown by MOVPE
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MOVPE 生长的立方 GaN/AlGaAs/GaAs(001) 各向异性缺陷结构的 TEM 研究
DOI：
10.1002/pssc.201001170
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
K. Onabe
中科院分区：
文献类型：
--
作者：
J. Parinyataramas;S. Sanorpim;C.Thanachayanont;K. Onabe
采用明场和暗场截面透射电子显微镜研究了在GaAs（001）衬底上低压金属有机物气相外延生长的立方（c-）GaN薄膜中插入AlxGa 1-xAs缓冲层对缺陷结构及其分布的影响。结果表明，300 nm厚的Al0.2Ga0.8As缓冲层可以保护GaAs（001）表面在960 °C下生长时不发生热分解，使c-GaN在GaAs衬底上生长，界面处没有任何空隙。观察到在[110]和[1 - 10]区轴之间具有各向异性分布的两种不同类型的缺陷结构。对于[110]区轴，观察到了金字塔形晶粒，这些晶粒被认为是由平面缺陷（如SF和孪晶）构成的。另一方面，对于[1 - 10]区轴，观察到具有较少平面缺陷贡献的致密立方相结构。然而，在c-GaN层的顶部区域观察到由金字塔形晶粒在[110]方向上的聚结产生的穿透位错。这两种类型的缺陷结构在立方对称性内具有各向异性分布，这可能是由于AlGaAs表面上沿着[110]和[1 - 10]结晶方向的不同原子结构。（© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA，魏因海姆）
The effects of AlxGa1‐xAs buffer layer insertion on the defect structures and their distribution in cubic (c‐) GaN films on GaAs (001) substrates grown by low‐pressure metalorganic vapor phase epitaxy have been investigated by means of bright‐ and dark‐field cross‐sectional transmission electron microscopy. It is demonstrated that a 300‐nm‐thick Al0.2Ga0.8As buffer layer can protect the GaAs (001) surface from thermal decomposition during the growth at 960 °C, remaining a growth of c‐GaN on GaAs substrate without any voids at the interface. Two different types of defect structures having an anisotropic distribution between the [110] and [1‐10] zone axes were observed. For the [110] zone‐axis, the pyramid‐shaped grains, which are proposed to construct from planar defects, such as SFs and twins, were observed. On the other hand, for the [1‐10] zone‐axis, a dense cubic phase structure with less contribution of planar defects was observed. However, threading dislocations, which were produced by a coalescence of pyramid‐shaped grains in the [110] direction, were observed at the top regions of c‐GaN layer. Both types of defect structures have an anisotropic distribution within a cubic symmetry that may be due to different atomic structures on the AlGaAs surface along the [110] and [1‐10] crystallographic directions. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)