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International Journal of Photoenergy
Volume 2016 (2016), Article ID 7218310, 5 pages
http://dx.doi.org/10.1155/2016/7218310
Research Article

High Quality GaAs Epilayers Grown on Si Substrate Using 100 nm Ge Buffer Layer

1Institute of Materials Science and Engineering, National Central University, Taoyuan, Taiwan
2Institute of Nuclear Energy Research, Taoyuan, Taiwan
3Optical Science Center, National Central University, Taoyuan, Taiwan
4Department of Optics and Photonics, National Central University, Taoyuan, Taiwan

Received 20 April 2016; Revised 27 July 2016; Accepted 17 August 2016

Academic Editor: Bhushan Sopori

Copyright © 2016 Wei-Cheng Kuo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We present high quality GaAs epilayers that grow on virtual substrate with 100 nm Ge buffer layers. The thin Ge buffer layers were modulated by hydrogen flow rate from 60 to 90 sccm to improve crystal quality by electron cyclotron resonance chemical vapor deposition (ECR-CVD) at low growth temperature (180°C). The GaAs and Ge epilayers quality was verified by X-ray diffraction (XRD) and spectroscopy ellipsometry (SE). The full width at half maximum (FWHM) of the Ge and GaAs epilayers in XRD is 406 arcsec and 220 arcsec, respectively. In addition, the GaAs/Ge/Si interface is observed by transmission electron microscopy (TEM) to demonstrate the epitaxial growth. The defects at GaAs/Ge interface are localized within a few nanometers. It is clearly showed that the dislocation is well suppressed. The quality of the Ge buffer layer is the key of III–V/Si tandem cell. Therefore, the high quality GaAs epilayers that grow on virtual substrate with 100 nm Ge buffer layers is suitable to develop the low cost and high efficiency III–V/Si tandem solar cells.