In situ construction of PtSe2/Ge Schottky junction array with interface passivation for broadband infrared photodetection and imaging

Abstract

Infrared (IR) detection is vital for various military and civilian applications. Recent research has highlighted the potential of two-dimensional (2D) topological semimetals in IR detection due to their distinctive advantages, including van der Waals (vdW) stacking, gapless electronic structure, and Van Hove singularities in the electronic density of states. However, challenges such as large-scale patterning, poor photoresponsivity, and high dark current of photodetectors based on 2D topological semimetals significantly impede their wider applications in low-energy photon sensing. Here, we demonstrate the in situ fabrication of PtSe₂/Ge Schottky junction by directly depositing 2D PtSe₂ films with a vertical layer structure on a Ge substrate with an ultrathin AlO_x layer. Due to high quality junction, the photodetector features a broadband response of up to 4.6 μm, along with a high specific detectivity of ~10¹² Jones, and operates with remarkable stability in ambient conditions as well. Moreover, the highly integrated device arrays based on PtSe₂/AlO_x/Ge Schottky junction showcases excellent Mid-IR (MIR) imaging capability at room temperature. These findings highlight the promising prospects of 2D topological semimetals for uncooled IR photodetection and imaging applications.