A High Performance Photodetector Suitable for Visible Light and Near Infrared Applications

Abstract

In this work, the high performance phototransistor photodetector (PTPD) in commercial 0.35 mm SiGe bipolar junction transistor complementary metal oxide semiconductor (BiCMOS) process without altering any process step is demonstrated and analyzed. The device combines a surface photodetector (SPD) and a conventional SiGe heterojunction transistor (HBT). It is shown that the SPD enhances light absorption, especially for the blue light. With the proper bias configuration, the PTPD shows acceptable dark current and a bias voltage that can be as low as 0.3 V. The Emitter and SPD areas can be respectively designed to meet electrical and optical requirements without increasing the device capacitance. Besides, high responsivities of 5.69/9.47/7.11 A/W for 450/670/780 nm lights were achieved in the PTPD, which makes the device suitable for many applications.