Design and Analysis of p-i-n-Type MoS2/Ge Heterojunction Photodetector

Wide spectrum, highly sensitive photodetectors are of great importance for many optoelectronic applications. MoS2 is an extremely desirable two-dimensional (2-D) material for fabricating high-performance photodetectors by forming van der Waals heterojunctions with conventional semiconductors. To address this issue, a p-i-n-type MoS2/Ge heterojunction photodetector based on multilayer MoS2 is proposed in this article, and the photodetector’s features are explored using simulations. The results show that the dark current of the detector is ${1.61} \times {10}^{-{17}}$ A, while the photocurrent is ${7.71} \times {10}^{-{7}}$ A at 0 V bias, showing a strong photovoltaic effect. Furthermore, the average responsivity of the photodetector is about 6 A/W in the spectral range of 200–1400 nm; the average noise equivalent power (NEP) and specific detectivity are in the range of $10^{-{18}}$ W/Hz $^{\text {1/2}}$ and $10^{{14}}$ Jones at zero bias voltage, respectively. The 3 dB bandwidth of the device at 1310 nm illumination is up to 19.2 GHz. These excellent performance metrics essentially indicate a massive potential of MoS2/Ge heterostructures for optoelectronic applications.