Stress and its effect on optical properties of GaN epilayers grown on Si(111), 6H-SiC(0001), and c-plane sapphire
Stress and its effect on optical properties of GaN epilayers grown on Si(111), 6H-SiC(0001), and c-plane sapphire
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DOI：
10.1063/1.1592306
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发表时间：
2003-07-28
影响因子：
4
通讯作者：
Yang, H
中科院分区：
文献类型：
--
作者：
Zhao, DG;Xu, SJ;Yang, H
利用室温共焦显微拉曼散射和光致发光技术研究了生长在Si（111）、6 H-SiC（0001）和c面蓝宝石衬底上的非故意掺杂GaN外延层中的应力状态及其对GaN薄膜光学性质的影响。在Si和6 H-SiC衬底上生长的GaN外延层存在较大的拉应力，而在蓝宝石衬底上生长的GaN外延层存在较小的压应力。后者表明在GaN/蓝宝石样品中插入的GaN缓冲层中的有效应变弛豫，而GaN/Si样品中采用的50 nm厚的AlN缓冲层保持高度应变。分析表明，外延层和衬底之间的热失配起着决定薄膜中的残余应变的主要作用。最后，得到表征GaN薄膜的发光带隙与双轴应力之间关系的线性系数为21.1+/-3.2meV/GPa。(C)2003年，美国物理学会。
The stress states in unintentionally doped GaN epilayers grown on Si(111), 6H-SiC(0001), and c-plane sapphire, and their effects on optical properties of GaN films were investigated by means of room-temperature confocal micro-Raman scattering and photoluminescence techniques. Relatively large tensile stress exists in GaN epilayers grown on Si and 6H-SiC while a small compressive stress appears in the film grown on sapphire. The latter indicates effective strain relaxation in the GaN buffer layer inserted in the GaN/sapphire sample, while the 50-nm-thick AlN buffer adopted in the GaN/Si sample remains highly strained. The analysis shows that the thermal mismatch between the epilayers and the substrates plays a major role in determining the residual strain in the films. Finally, a linear coefficient of 21.1+/-3.2 meV/GPa characterizing the relationship between the luminescent bandgap and the biaxial stress of the GaN films is obtained. (C) 2003 American Institute of Physics.