Enhanced Signal-to-Noise Ratio of Ge/Ge1-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-Ge1-xSnx/n-Ge Heterojunction Transistor (HPT) with multiple quantum well (MQW) inserted in the base and different base-width for efficient detection at 1.55 mu m. 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 >61 dB up to 100 GHz can be achieved, which ensures the operation of the device in the high-frequency range and low-noise detector.