2D SnSe/Si heterojunction for self-driven broadband photodetectors

Abstract

Van der Waals heterojunctions based on atomically thin 2D materials have opened up new realms in modern semiconductor industry. However, it is still challenging to fabricate large-area ultrathin 2D films. Herein, we successfully fabricate wafer-size 2D SnSe films on Si substrate by magnetron sputtering technique, enabling the formation of SnSe/Si van der Waals (vdWs) heterojunction device. The high-resolution transmission electron microscopy is employed to character the structure of SnSe film and SnSe/Si heterojunction with ideal orthorhombic structure and atomically abrupt interface, respectively. The energy diagram of SnSe/Si heterojunction is constructed, exhibiting similar barrier heights for electron and hole carrier. The SnSe/Si heterojunction shows obvious diode behavior with rectification ratio of ∼1.6 ×10 ⁴ , forward current of ∼194.5 mA cm ^-2 at ±1.0 V. Furthermore, owing to the high crystalline orientation, specific energy-band alignment, as well as the strong built-in electrical field, the SnSe/Si heterojunction illustrates a broadband photodetecting properties with the wavelength ranging from ultraviolet to near-infrared light, showing a high detectivity of 4.4 ×10 ¹² cmHz ^1/2 W ^-1 , a high responsivity of 566.4 mA mW ^-1 and an ultrafast response/recovery time of ∼1.6/47.7 s under zero external bias. This work provides a new strategy for fabrication of low cost 2D optoelectronic devices with high-performance.