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 View the MathML source at View the MathML source and View the MathML source at View the MathML source under the reversed bias of View the MathML source. For electrical DC and microwave performance, the SiGe HBT has a current gain of 160 and a cut-off frequency (fT) of View the MathML source, respectively.