Cheng, T.-H.T.-H.ChengPeng, K.-L.K.-L.PengKo, C.-Y.C.-Y.KoChen, C.-Y.C.-Y.ChenLan, H.-S.H.-S.LanYUH-RENN WUCHEE-WEE LIUTseng, H.-H.H.-H.Tseng2018-09-102018-09-10201000036951http://www.scopus.com/inward/record.url?eid=2-s2.0-77956244835&partnerID=MN8TOARShttp://scholars.lib.ntu.edu.tw/handle/123456789/358243https://www.scopus.com/inward/record.uri?eid=2-s2.0-77956244835&doi=10.1063%2f1.3429085&partnerID=40&md5=f6e516badfad4ffcd4d62a41f5cec12fStrong enhancement of Ge direct transition by biaxial-tensile strain was observed. The reduction in band gap difference between the direct and indirect valleys by biaxial tensile strain increases the electron population in the direct valley, and enhances the direct transition. The band gap reduction in the direct and indirect valleys can be extracted from the photoluminescence spectra and is consistent with the calculations using kp and deformation potential methods for conduction bands and valence bands, respectively. © 2010 American Institute of Physics.Band gap reduction; Biaxial tensile strain; Deformation potential; Direct transition; Electron population; In-band; Photoluminescence spectrum; Strong enhancement; Electron mobility; Energy gap; Germanium; Landforms; Photoluminescence; Tensile strainjournal article10.1063/1.34290852-s2.0-77956244835