Modulation of Junction Modes in SnSe 2 /MoTe 2 Broken-Gap van der Waals Heterostructure for Multifunctional Devices.

We study the electronic and optoelectronic properties of a broken-gap heterojunction composed of SnSe ₂ and MoTe ₂ with gate-controlled junction modes. Owing to the interband tunneling current, our device can act as an Esaki diode and a backward diode with a peak-to-valley current ratio approaching 5.7 at room temperature. Furthermore, under an 811 nm laser irradiation the heterostructure exhibits a photodetectivity of up to 7.5 × 10 ¹² Jones. In addition, to harness the electrostatic gate bias, V _oc can be tuned from negative to positive by switching from the accumulation mode to the depletion mode of the heterojunction. Additionally, a photovoltaic effect with a fill factor exceeding 41% was observed, which highlights the significant potential for optoelectronic applications. This study not only demonstrates high-performance multifunctional optoelectronics based on the SnSe ₂ /MoTe ₂ heterostructure but also provides a comprehensive understanding of broken-band alignment and its applications.