Raman study of biaxial strain in InGaN-GaN self-assembled quantum dots grown on sapphire (0001)

摘要

In this study, we have prepared 3 samples as follow: 2-μm-thick GaN on sapphire, 2.4-nm thick InGaN with SAQDs/GaN/sapphire, and 100-nm thick InGaN/GaN/sapphire. By means of Raman spectroscopy, the smaller E_2~H peaks blueshift were observed from 100-nm thick InGaN/GaN/sapphire due to their InGaN epilayers could relax partially biaxial strain. On the contrary, 2.4-nm thick InGaN with the InGaN QD structures of high strain shows a strong compressive stress in InGaN layer.