Thickness effect of 2D PdSe2 film on performance of PdSe2/Si heterostructure photodetectors

Abstract Two-dimensional (2D) PdSe 2 film has the characteristics of adjustable bandgap, high carrier mobility, and high stability. Photodetector (PD) based on 2D PdSe 2 exhibits wide spectral self-driving features, demonstrating enormous potential in the field of optical detection. Here, we design and fabricate PdSe 2 /Si heterojunction PDs with various thicknesses of the PdSe 2 films from 10 to 35 nm. Due to the enhancement of light absorption capacity and built-in electric field of heterojunction, the photodetector with thicker PdSe 2 film can generate more photo-generated carriers and effectively separate them to form a large photocurrent, thus showing more excellent photodetection performance. The responsivity and specific detectivity of the PdSe 2 /Si PDs with 10 nm, 20 nm, and 35 nm PdSe 2 films are 2.12 A W −1 and 6.72 × 10 9 Jones, 6.17 A W −1 and 1.95 × 10 10 Jones, and 8.02 A W −1 and 2.54 × 10 10 Jones, respectively (808 nm illumination). The PD with 35 nm PdSe 2 film exhibits better performance than the other two PDs, with the rise/fall times of 15.8 μ s/138.9 μ s at f = 1 kHz and the cut-off frequency of 8.6 kHz. Furthermore, we demonstrate that the properties of PdSe 2 /Si PD array have excellent uniformity and stability at room temperature and shows potential for image sensing in the UV–vis-NIR wavelength range.