Band structure engineering of strained and doped germanium nanowires and 2D layers

Germanium has been highly investigated as a potential light emitting material for the integration of photonic devices on silicon-based electronics. In the search of merging electronics and photonics using only silicon and germanium as base materials, many unsuccessful attempts were made in the past to fabricate an efficient group IV light source. Indeed, these semiconductors are known to be poor light emitters, due to the indirect nature of their forbidden band gap. This limitation seems today mitigated after the recent demonstration by the J. Michel group at MIT that a germanium waveguide with suitable doping and strain could reach pulsed laser operation at the direct band gap [1]. Here we present here an experimental study of the phosphorus doping and tensile strain of both Vapor-Liquid-Solid (VLS) grown germanium nanowires and low temperature grown 2d germanium layers on silicon.