Deterministic Light-to-Voltage Conversion with a Tunable Two-Dimensional Diode

Heterojunctions accompanied by energy barriers are of significant importance in two-dimensional materials-based electronics and optoelectronics. They provide more functional device performance, compared with their counterparts with uniform channels. Multimodal optoelectronic devices could be accomplished by elaborately designing band diagrams and architectures of the two-dimensional junctions. Here, we demonstrate deterministic light-to-voltage conversion based on strong dielectric screening effect in a tunable two-dimensional Schottky diode based on semiconductor/metal heterostructure, where the resultant photovoltage is dependent on the intensity of light input but independent of gate voltage. The converted photovoltage across the diode is independent of gate voltage under both monochromatic laser and white light illumination. In addition, the Fermi level of two-dimensional semiconductor area on dielectric SiO2 is highly gate-dependent, leading to the tunable rectifying effect of this heterostructure, which corporates a vertical Schottky junction and a lateral homojunction. As a result, a constant open-circuit voltage of similar to 0.44 V and a hybrid photovoltaic + photoconduction photoresponse behavior are observed under 1 mu W illumination of 403 nm laser, in addition to an electrical rectification ratio up to nearly 10(4). The scanning photocurrent mappings under different bias voltages indicate that the switchable operation mode (photovoltaic, photoconduction, or hybrid) depends on the bias-dependent effective energy barrier at the two-dimensional semiconductor-metal interface. This approach provides a facile and reliable solution for deterministic on-chip light-to-voltage conversion and optical-to-electrical interconnects.

Automated summary

This study investigates the application of heterojunctions and energy barriers in two-dimensional materials-based optoelectronic devices. By elaborately designing the band diagrams and architectures of two-dimensional junctions, multimodal optoelectronic devices are achieved. The research focuses on the semiconductor/metal heterostructure, which shows great potential for light-to-voltage conversion and offers a convenient and reliable solution for deterministic on-chip light-to-voltage conversion and optical-to-electrical interconnects.