Improving Optical Properties of Ge Layers Fabricated by Epitaxial Growth Combined with Ge Condensation

Single crystal Ge layers were successfully fabricated on the buried oxide layer of a silicon-on-insulator wafer using a combined technique of two-step selective epitaxial growth and Ge condensation. X-ray diffraction measurements revealed that the single crystal Ge layer formed on the buried oxide layer had a tensile strain of 0.07% on the < 110 > lattice plane in a large unpatterned area. Furthermore, a steep photoluminescence spectrum was obtained from Ge stripes fabricated on the buried oxide layer, and a red shift in the photoluminescence peak was observed due to tensile strain with a wavelength of 1620 nm. The peak intensity of a 10-mm-wide Ge stripe on the buried oxide layer was three times higher than that on a Ge stripe on an Si substrate, which was achieved by improving the crystallinity and carrier confinement within the Ge stripes. These results indicate that this combined technique efficiently improves the performance of Ge light-emitting devices. (C) 2012 The Japan Society of Applied Physics