Control of Initial Nucleation by Reducing the V/III Ratio during the Early Stages of GaN Growth
Control of Initial Nucleation by Reducing the V/III Ratio during the Early Stages of GaN Growth
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DOI：
10.1002/1521-396x(200007)180:1
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发表时间：
2000-07
期刊：
影响因子：
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通讯作者：
Tao Yang;K. Uchida;T. Mishima;J. Kasai;J. Gotoh
中科院分区：
文献类型：
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作者：
Tao Yang;K. Uchida;T. Mishima;J. Kasai;J. Gotoh
利用原子力显微镜（AFM）研究了高温GaN生长初期V/III比对GaN外延层表面形貌的影响。采用低压金属有机物化学气相沉积（LP-MOCVD）方法在蓝宝石衬底上生长外延层。我们观察到，当在低温（LT）GaN缓冲层生长期间或在HT-GaN生长的早期阶段（HT-GaN缓冲生长）期间使用较低的V/III比时，HT-GaN生长早期阶段的初始HT-GaN岛较大。当在LT-GaN缓冲层生长期间使用较低的V/III比时，这些较大的岛归因于降低的核密度，或者当在HT-GaN生长的早期阶段使用较低的V/III比时，归因于增加的生长纵横比（垂直和横向生长速率的比率）。较大的岛导致较少的缺陷时，他们合并，这表明，通过LP-MOCVD生长在蓝宝石衬底上的GaN外延层的质量可以通过在LT或HT GaN缓冲层生长期间使用低V/III比来改善。
We investigated, by atomic force microscopy (AFM), the effect of the V/III ratio on the surface morphologies of GaN epilayers during the early stage of high-temperature (HT) GaN growth. The epilayers were grown on sapphire substrates by low-pressure metal-organic chemical vapor deposition (LP-MOCVD). We observed that initial HT-GaN islands in the early stage of HT-GaN growth were larger when a lower V/III ratio was used during the low-temperature (LT) GaN-buffer-layer growth or during the early stage of HT-GaN growth (the HT-GaN-buffer growth). These larger islands were attributed to a reduced nuclei density when a lower V/III ratio was used during the LT-GaN-buffer-layer growth, or to an increased growth aspect ratio (the ratio of vertical and lateral growth rates) when a lower V/III ratio was used in the early stage of HT-GaN growth. The larger islands led to fewer defects when they coalesced, which demonstrated that the quality of GaN epilayers grown on sapphire substrates by LP-MOCVD can be improved by using a low V/III ratio during the LT or HT GaN-buffer-layer growth.