Facile fabrication of amorphous-In2Se3/Si heterojunction for fast ultraviolet to near-infrared broadband photodetection

Abstract

Indium selenide (In2Se3) has emerged as a promising candidate for broadband photodetection due to its suitable bandgap, high electron mobility, high optical absorption coefficient, and broad-spectrum absorption properties. Nevertheless, wafer-scale growth of single-component and pure-phase In2Se3 films remains challenging and requires stringent experimental parameters. Here, a facile approach for depositing amorphous-In2Se3 (a-In2Se3) on Si substrate by physical vapor deposition (PVD) process is proposed to fabricate high-performance a-In2Se3/Si heterojunction photodetectors. The as-produced devices are sensitive to a broad-spectrum (255–1300 nm), exhibiting superior overall performance with a low dark current of 0.54 nA, large current on/off ratio of 2.26 × 104, fast response with rise/decay time of 176/175 μs, decent responsivity of 1.50 A/W and detectivity of 6.46 × 1012 Jones under 1050 nm illumination at − 3 V bias. Such remarkable results can be attributed to the unique type-Ⅰ straddling energy band alignment and the strong coupling between a-In2Se3 and Si interface. In addition, decent responsivity and detectivity under 255 nm (0.29 A/W and 1.25 × 1012 Jones) and 630 nm (0.77 A/W and 3.32 × 1012 Jones) remedy the deficiency of Si in ultra-violet and visible light detection. Our work provides a facile and low-cost route for the realization of high-performance broadband photodetectors based on a-In2Se3/Si heterojunctions.