Growth Mechanism and Strain Variation of GaN Material Grown on Patterned Sapphire Substrates With Various Pattern Designs
Growth Mechanism and Strain Variation of GaN Material Grown on Patterned Sapphire Substrates With Various Pattern Designs
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DOI：
10.1109/lpt.2011.2147778
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发表时间：
2011-07-15
影响因子：
2.6
通讯作者：
Li, Yun-Li
中科院分区：
文献类型：
--
作者：
Wang, Mei-Tan;Liao, Kuan-Yung;Li, Yun-Li
研究了在具有各种图案设计的图案化蓝宝石衬底（PSS）上生长的 GaN 材料的生长机制和应变变化。通过场发射扫描电子显微镜 (SEM) 展示了在梯形 PSS (TPSS) 和锥形 PSS (CPSS) 上生长的 GaN 外延层的时间演化。从透射电子显微镜（TEM）观察来看，CPSS 的螺纹位错（TD）小于 TPSS。通过微拉曼光谱测量在 PSS 上生长的 GaN 外延层中的空间相关应变。 6μm周期TPSS的残余应变大小为Delta，约为0.97GPa，6μm周期CPSS的残余应变大小为GPa。另一方面，较短周期（3μm周期PSS）的设计可以进一步释放外延GaN薄膜的残余应变。实验结果表明，短周期CPSS比TPSS具有更好的外延质量和更小的残余应变。
Growth mechanism and strain variation of GaN material grown on patterned sapphire substrates (PSS) with various pattern designs are investigated. Time evolutions of GaN epi-layer grown on trapezoid-shaped PSS (TPSS) and cone-shaped PSS (CPSS) are demonstrated by field emission scanning electron microscopy (SEM). From the transmission electron microscopy (TEM) observations, the threading dislocations (TDs) of CPSS is less than that of TPSS. Space-depended strain in GaN epi-layer grown on PSS is measured by micro-Raman spectroscopy. The magnitude of residual strain of 6-mu m-period TPSS is Delta approximate to 0.97 GPa and that of 6-mu m-period CPSS is GPa. On the other hand, a design of shorter period (3-mu m-period PSS) could further release residual strain of epitaxial GaN thin film. Based on experimental results, it is suggested that the CPSS with short period has better epitaxial quality and less residual strain than TPSS.