Light-triggered two-dimensional lateral homogeneous p-n diodes for opto-electrical interconnection circuits

The realization of light-triggered devices where light is used as external stimulus to control the device performances is a long-standing goal in modern opto-electrical interconnection circuits. In this work, it reveals that light illumination can induce the formation of p-n junctions along two-dimensional conduction channels. The results indicate that the dominant charge carrier type and density in black phosphorus (BP) conduction channel can be effectively modulated by the underlying cadmium sulfide (CdS) photogate layer under light illumination. This enables flexible switching of the working state between BP resistor and BP p-n diode in the designed semi-photo-gate transistor (SPGT) devices when switching the light on and off (ultra-low threshold light power). Simultaneously, the achieved BP p-n junctions also exhibit ultra-high photoresponsivity and evident photovoltaic properties. That is to say, light can be employed as external stimulus to define the BP p-n junctions, and in turn the p-n junctions will further convert the light into electrical power, showing all-in-one opto-electrical interconnection properties. Moreover, the SPGT device architecture is also applicable for construction of other ambipolar semiconductor-based (WSe2- and MoTe2-based) p-n diodes. Such universal all-in-one light-triggered lateral homogeneous p-n junctions with ultra-low energy consumption should open a new pathway toward novel optoelectronic devices and deliver various new applications. (C) 2019 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.