Growth and characterization of highly tensile strained Ge1− x Sn x formed on relaxed In y Ga1− y P buffer layers

• Published in: Journal of applied physics 2016-03, Vol.119 (12)
• Main Authors: Wang, Wei, Loke, Wan Khai, Yin, Tingting, Zhang, Zheng, D'Costa, Vijay Richard, Dong, Yuan, Liang, Gengchiau, Pan, Jisheng, Shen, Zexiang, Yoon, Soon Fatt, Tok, Eng Soon, Yeo, Yee-Chia
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4944718

Ge0.94Sn0.06 films with high tensile strain were grown on strain-relaxed In y Ga1− y P virtual substrates using solid-source molecular beam epitaxy. The in-plane tensile strain in the Ge0.94Sn0.06 film was varied by changing the In mole fraction in In x Ga1− x P buffer layer. The tensile strained Ge0.94Sn0.06 films were investigated by transmission electron microscopy, x-ray diffraction, and Raman spectroscopy. An in-plane tensile strain of up to 1% in the Ge0.94Sn0.06 was measured, which is much higher than that achieved using other buffer systems. Controlled thermal anneal experiment demonstrated that the strain was not relaxed for temperatures up to 500 °C. The band alignment of the tensile strained Ge0.94Sn0.06 on In0.77Ga0.23P was obtained by high resolution x-ray photoelectron spectroscopy. The Ge0.94Sn0.06/In0.77Ga0.23P interface was found to be of the type I band alignment, with a valence band offset of 0.31 ± 0.12 eV and a conduction band offset of 0.74 ± 0.12 eV.