Uniformity and control of surface morphology during growth of GaN by molecular beam epitaxy
Uniformity and control of surface morphology during growth of GaN by molecular beam epitaxy
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分子束外延生长GaN过程中表面形貌的均匀性和控制
DOI：
10.1116/1.1993615
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发表时间：
2005
影响因子：
1.4
通讯作者：
J. Speck
中科院分区：
文献类型：
--
作者：
C. Poblenz;P. Waltereit;J. Speck
在射频等离子体辅助氮化镓分子束外延过程中，引入了一种“调制生长”技术来实现大面积均匀性和表面形貌控制。该技术包括通过Ga、N或Ga和N一起的短周期遮光（例如，50-100A生长周期）来调制Ga的表面覆盖，以实现（0001）GaN表面上Ga的高低表面覆盖交替。高Ga通量的生长周期在整个晶圆上提供了Ga （~ 2.5 ML Ga加Ga液滴）的饱和覆盖，而随后的低Ga通量生长周期则促进了时间平均的Ga通量，该通量刚好低于生长温度下液滴形成的交叉点。随着时间的推移，低Ga通量的生长抑制了液滴的积累，这对于保持光滑、无凹点的表面形态是必要的。利用反射高能电子衍射和视距四极质谱仪对这一过程进行了现场监测。
A “modulated growth” technique has been introduced to achieve large area uniformity and surface morphology control during rf plasma assisted molecular beam epitaxy of GaN. The technique consists of modulating the surface coverage of Ga through short-period shuttering of Ga, N, or Ga and N together (e.g., 50–100A growth periods), to achieve alternating high and low surface coverages of Ga on the (0001) GaN surface. The periods of growth with high Ga flux provide saturation coverage of Ga (∼2.5 ML Ga plus Ga droplets) over the full wafer, while the subsequent growth with low Ga flux facilitates a time-averaged Ga flux which is just below the crossover for droplet formation at the growth temperature. The growth transients in the Ga droplet regime are necessary to maintain smooth, pit-free surface morphologies, and the subsequent growth with low Ga flux suppresses droplet buildup over time. The process is monitored in situ utilizing reflection high energy electron diffraction and line-of-sight quadrupole mass...