Enhanced Signal-to-Noise Ratio of Ge/Gei-xSnX/Ge based Multiple Quantum Well Heterojunction Phototransistor for SWIR Photodetection

We have studied noise characteristics and signal-to-noise ratio (SNR) of n-Ge/p-Ge_1-xSn_x/n-Ge Heterojunction Transistor (HPT) with multiple quantum well (MQW) inserted in the base and different base-width for efficient detection at 1.55 μm . The MQW inserted in the base significantly improves SNR in the high-frequency region, leading to efficient detection in the fiber-optic telecommunication windows. The results show that SNR is not only dependent on the frequency, but also on the base-width and number of quantum wells (QWs). The estimated result shows that SNR of > 61dB up to 100 GHz can be achieved, which ensures the operation of the device in the high-frequency range and low-noise detector.