Si1−xGex/Si multi-quantum well phototransistor for near-infrared operation

For the first time in the literature, we report the monolithic integration of SiGe near-infrared phototransistor and planar hetero-junction bipolar transistor (HBT). The phototransistor is made with SiGe/Si multi-quantum well structure (MQW_PHT). At room temperature, the MQW_PHT reveals an optical responsivity of 1904mW/A at 0.85μm and 1.25mW/A at 1.3μm under the reversed bias of VCE=1.5V. For electrical DC and microwave performance, the SiGe HBT has a current gain of 160 and a cut-off frequency (fT) of 25GHz, respectively.