The impact of graphene properties on GaN and AlN nucleation
The impact of graphene properties on GaN and AlN nucleation
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DOI：
10.1016/j.susc.2014.11.020
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发表时间：
2015-04-01
期刊：
影响因子：
1.9
通讯作者：
Robinson, Joshua A.
中科院分区：
文献类型：
--
作者：
Al Balushi, Zakaria Y.;Miyagi, Takahira;Robinson, Joshua A.
由于sp（2）杂化碳原子的六方排列类似于纤锌矿GaN的（0001）c平面，因此使用石墨烯作为用于III族氮化物（GaN和AlN）的异质外延的模板层已经引起了兴趣。在这项研究中，GaN和AlN的成核的金属有机化学气相沉积上的准独立的外延石墨烯（EG）进行了研究。我们观察到AlN和GaN的成核是沿着周期性（1（1）比棒0 n）EG涂覆的台阶边缘和（0001）台阶上的缺陷位置的优先成核，这是由于在这些区域处的增强的化学反应性。EG的（0001）平台上的核密度随着经由NH3暴露将氮缺陷并入石墨烯晶格中而增加，如通过XPS的表面化学分析所证明的。拉曼光谱映射表明，GaN选择性地成核的区域的几层EG，而不是区域的多层EG。HR-TEM还揭示了EG底层在GaN成核区域中是高度缺陷的，然而，GaN核是单晶的，c轴取向的，并且没有螺纹位错。与此相反，AlN的多晶岛被发现成核EG而不产生的基础EG中的障碍。(C)2014爱思唯尔有限公司版权所有。
The use of graphene as a template layer for the heteroepitaxy of III-nitrides (GaN and AlN) has gained interest due to the hexagonal arrangement of the sp(2) hybridized carbon atoms being similar to the (0001) c-plane of wurtzite GaN. In this study, the nucleation of GaN and AlN by metalorganic chemical vapor deposition on quasi-free standing epitaxial graphene (EG) was investigated. We observed that the nucleation of AlN and GaN was preferential along the periodic (1 (1) over bar 0n) EG coated step edges and at defects sites on the (0001) terraces due to the enhanced chemical reactivity at those regions. The density of nuclei on the (0001) terraces of EG increased with the incorporation of nitrogen defects into the graphene lattice via NH3 exposure as was evident from surface chemical analysis by XPS. Raman spectral mapping showed that GaN selectively nucleates on regions of few-layered EG as opposed to regions of multi-layered EG. HR-TEM also revealed that the EG underlayers were highly defective in the region of GaN nucleation, however, the GaN nuclei were single crystalline, c-axis oriented and were free of threading dislocations. In contrast, polycrystalline islands of AlN were found to nucleate on EG without producing disorder in the underlying EG. (C) 2014 Elsevier B.V. All rights reserved.