PtSe2 Thickness Engineering Towards Fast Response, Large Linear Dynamic Range, and Broadband PtSe2/Si Heterojunction Photodetector

Abstract

Two-dimensional (2D) material/Si van der Waals heterojunctions exhibit exceptional photodetection capabilities and have garnered significant attention in the research community. The thickness of 2D materials plays a crucial role in determining the performance of these heterojunctions, an aspect that has yet to be comprehensively studied. In this study, we systematically investigated the electrical and photodetection properties of PtSe₂/Si heterojunctions with varying PtSe₂ thicknesses. The device with a 9 nm-thick PtSe₂ layer achieved the highest rectification ratio of 9.0 × 10⁶ at ±2 V. Within the 350 – 1100 nm spectral range, the device featuring a 3 nm-thick PtSe₂ layer demonstrated the highest responsivity (0.49 A/W at 950 nm under −2 V bias), while the 9 nm-thick PtSe₂ device exhibited the highest specific detectivity (9.1 × 10¹² Jones at 800 nm under 0 V bias). Additionally, the 9 nm-thick PtSe₂ device showcased an exceptional linear dynamic range (LDR) of 157 dB, a response speed with rise and decay times of 38 μs and 51 μs, respectively, and a 3dB bandwidth of 12.7 kHz. At 1550 nm, the device with a 12 nm-thick PtSe₂ layer delivered superior performance, achieving a responsivity of 1.4 μA/W, an LDR of 110 dB, and a specific detectivity of 1.4 × 10⁷ Jones. These results highlight the potential of PtSe₂/Si heterojunctions to deliver broadband spectral response and competitive performance metrics, making them highly promising for future optoelectronic applications.