Triggered luminescence in a strained Si1−xGex/Si single quantum well with surface as an electron reservoir

It is demonstrated that strained Si1−xGex/Si single quantum wells (SQWs) are capable of generating light pulses simply by controlling the population of only one type of carriers in the SQW through longitudinal electric fields. The unique band lineup of strained Si1−xGex/Si QWs allows loose confinement of electrons, which makes the electrons easy to be detrapped upon application of electric field. At a weak positive surface bias, an electron reservoir is formed in the near-surface region while holes stay in the QW so that electrons and holes are spatially apart and thereby luminescence signal is diminished. Upon removal of the bias voltage, the electrons that have built up in the near-surface are driven back to the QW, turning on luminescence. Triggered 50 ns light pulse train was generated with alternating bias voltage waveform for a single-shot excitation of electron-hole pairs at the outset.