Abstract
The behavior of direct and indirect valleys in Ge, and the bandgap shrinking, under different tensile-strain conditions in bulk Ge and Ge quantum well structures are explored using the deformation potential and k . p methods. The doping density required for filling the indirect valleys up to the Gamma-valley is calculated for various strain and growth conditions, as well as the efficiency of electron injection into the Gamma-valley, and the optimum cases for Ge laser operation are identified. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3691790]