Electroluminescence from Strained Ge membranes and Implications for an   Efficient Si-Compatible Laser
  We demonstrate room-temperature electroluminescence (EL) from light-emitting diodes (LED) on highly strained germanium (Ge) membranes. An external stressor technique was employed to introduce a 0.76% bi-axial tensile strain in the active region of a vertical PN junction. Electrical measurements show an on-off ratio increase of one order of magnitude in membrane LEDs compared to bulk. The EL spectrum from the 0.76% strained Ge LED shows a 100nm redshift of the center wavelength because of the strain-induced direct band gap reduction. Finally, using tight-binding and FDTD simulations, we discuss the implications for highly efficient Ge lasers. 
Donguk Nam, David Sukhdeo, Szu-Lin Cheng, Arunanshu Roy, Kevin   Chih-Yao Huang, Mark Brongersma, Yoshio Nishi, and Krishna ...
physics.optics cond-mat.mtrl-sci