Band structure of silicon and germanium thin films based on first principles<xref rid="cpb_26_3_037302fn1" ref-type="fn">*</xref> <fn id="cpb_26_3_037302fn1"><label>*</label><p>Project supported by the National Natural Science Foundation of China (Grant Nos. 11264007 and 61465003).</p></fn>

Band structure of silicon and germanium thin films based on first principles* *

Project supported by the National Natural Science Foundation of China (Grant Nos. 11264007 and 61465003).

Wu Xue-Ke^{¹, ²}, Huang Wei-Qi^{², †}, Huang Zhong-Mei^³, Qin Chao-Jian^⁴, Dong Tai-Ge^², Wang Gang^², Tang Yan-Lin^{², ‡}

(color online) (a) Direct band gap transition to indirect band gap in 7 unit cells thickness of (111) face sandwich structure with the increasing of Ge layer proportion (x). (b) The critical values of the transition of indirect band gap to direct band gap in sandwich structure of (111) and (100) surfaces.