Effects of the sapphire nitridation on the polarity and structural properties of GaN layers grown by plasma-assisted MBE
Effects of the sapphire nitridation on the polarity and structural properties of GaN layers grown by plasma-assisted MBE
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DOI：
10.1002/1521-396x(200112)188:2
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发表时间：
2001-11-23
期刊：
影响因子：
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通讯作者：
Karakostas, T
中科院分区：
文献类型：
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作者：
Georgakilas, A;Mikroulis, S;Karakostas, T
研究了 GaN 分子束外延中使用的氮射频等离子体源对 (0001) 蓝宝石表面的氮化。俄歇电子能谱测量用于估计氮化效应的程度。在700℃的高温（HT）下100分钟内发生显着的氮化，氮化层通常呈现三维岛状，而在165℃的低温（LT）下发生弱氮化并导致原子级平坦的表面。已经发现 HT 氮化量具有线性时间依赖性。高氮化温度导致过度生长的GaN薄膜的Ga面和N面极性温度较低。电子显微镜观察表明，N 面材料尽管表面粗糙度较高，但仍表现出优异的结晶质量。
The nitridation of the (0001) sapphire surface by a nitrogen rf-plasma source used in GaN molecular beam epitaxy has been investigated. Auger electron spectroscopy measurements were used to estimate the extent of the nitridation effect. Significant nitridation occurred during 100 min at a high temperature (HT) of 700 degreesC and the nitridated layers usually exhibited three-dimensional islands, while weak nitridation occurred at a low temperature (LT) of 165 degreesC and resulted to atomically flat surfaces. Linear time dependence has been found for the amount of HT nitridation. High nitridation temperature resulted in Ga-face and low temperature in N-face polarities of overgrown GaN films. Electron microscopy observations revealed that the N-face material exhibited a superior crystalline quality although presented higher surface roughness.