MoS2/Si-Based Heterojunction Bipolar Transistor as a Broad Band and High Sensitivity Photodetector

MoS2 has been well established as a promising two-dimensional candidate for optoelectronic applications, due to its unique optical and electrical properties. Here, we report fabrication of a novel heterojunction bipolar transistor (HBT) based on MoS2/Si heterojunction for the first time. Optoelectronic properties of the fabricated MoS2/Si-based HBT confirm the high-sensitivity of the device to a broad range of incident wavelengths from 380 nm to 810 nm. A Responsivity of about 400 A/W, one order of magnitude higher than the previously reported MoS2 based photodetectors, and a gain of about 1200 are obtained in response to the incident wavelength of 380 nm by the fabricated device. Our results open up a way to fabricate highly sensitive broad band photodetectors with a simple and low cost fabrication process, suitable for Si-based integrated electronics.