Voltage-controlled emission wavelength switching in a pseudomorphic Si1-xGex/Si double quantum well

Voltage-controlled emission wavelength switching (VCEWS) is demonstrated in a pseudomorphic Si1-xGex/Si double quantum well (DQW). Under cw excitation, photoluminescence (PL) of the DQW was found to exhibit a clear switchover of emission wavelengths under longitudinal electric field, where an extinction ratio of more than 100 was obtained. In the time domain, antiphase oscillations of PL decays synchronized with the polarity switch of driving voltages were observed. The unique band line-up of pseudomorphic Si1-xGex/Si QWs which makes loosely bound electrons susceptible to longitudinal electric fields underlies the operation of VCEWS.