Control of GaN surface morphologies using plasma-assisted molecular beam epitaxy
Control of GaN surface morphologies using plasma-assisted molecular beam epitaxy
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DOI：
10.1063/1.1305830
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发表时间：
2000-08-15
影响因子：
3.2
通讯作者：
Speck, JS
中科院分区：
文献类型：
--
作者：
Heying, B;Averbeck, R;Speck, JS
研究了等离子体辅助分子束外延生长的GaN在不同生长条件下的特征表面形貌。三种生长制度（一个N稳定和两个Ga稳定）确定的表面结构图（Ga/N比与衬底温度）。N-稳定的制度（低Ga/N比）和两个Ga-稳定的制度（高Ga/N比）之间的边界是由薄膜的生长速率，并在衬底温度的范围内是恒定的调查。两个Ga稳定制度（Ga液滴制度和中间制度）之间的边界由Ga液滴的形成决定，并与衬底温度具有阿仑尼乌斯依赖性。这些制度内生长的薄膜的特征形态进行了研究，使用原子力显微镜和透射电子显微镜。N-稳定膜具有粗糙、严重凹坑的形态。在中间相内生长的膜在大的、不规则形状的凹坑之间具有平坦表面区域。发现在这两个制度内生长的膜所观察到的坑从螺纹位错开始，并在恒定温度下随着Ga/N比的增加而降低密度。镓稳定的薄膜，生长在镓液滴制度，表现出原子级平坦的表面，没有坑的功能。的形态转变与生长动力学的变化所造成的GaN表面的覆盖率由过量的Ga的变化。(C)2000年美国物理学会。[S0021-8979（00）02416-6]。
The characteristic surface morphologies of GaN grown by plasma-assisted molecular beam epitaxy under various growth conditions have been investigated. Three growth regimes (one N stable and two Ga stable) are identified on a surface structure diagram (Ga/N ratio versus substrate temperature). The boundary between the N-stable regime (low Ga/N ratios) and the two Ga-stable regimes (high Ga/N ratios) is determined by the growth rate of the films and is constant over the range of substrate temperatures investigated. The boundary between the two Ga-stable regimes (the Ga-droplet regime and the intermediate regime) is determined by the formation of Ga droplets and has an Arrhenius dependence with substrate temperature. The characteristic morphologies of films grown within each of these regimes are investigated using atomic force microscopy and transmission electron microscopy. N-stable films have rough, heavily pitted morphologies. Films grown within the intermediate phase have areas of flat surface between large, irregularly shaped pits. The pits observed for films grown within both regimes are found to initiate from threading dislocations and to decrease in density with increasing Ga/N ratio at constant temperature. Ga-stable films, grown within the Ga-droplet regime, exhibit atomically flat surfaces with no pit features. The morphology transitions are associated with changes in the growth kinetics caused by variations in the coverage of the GaN surface by excess Ga. (C) 2000 American Institute of Physics. [S0021-8979(00)02416-6].