Light-Triggered and Polarity-Switchable Homojunctions for Optoelectronic Logic Devices

Semiconductor homojunctions based on 2D materials are promising candidates for optoelectronic logic devices due to their excellent electrostatic tunability and photoelectric characteristic. However, to reach programmable logic functions, the 2D homojunctions usually suffer from compulsory combinations of electrical and optical inputs. Here, a light-triggered and polarity-switchable homojunction made from the vertically stacked MoTe2/CuInP2S6/Au layers in a dual-floating gate transistor configuration, is demonstrated. Utilizing the band alignment between MoTe2 and CuInP2S6, the photocarriers in MoTe2 can be excited to Au layer across the insulating CuInP2S6 efficiently, serving as floating gate to modulate the polarity of the MoTe2 homojunctions which produce photocurrents simultaneously in photovoltaic mode. A logic gate XOR is achieved in one single device without the need for any applied voltage. Moreover, the devices exhibit both anomalous photoresponse and optical memory behaviors in photoconductive mode. The results provide a potential route for the development of optoelectronic logic devices with fully light-actuated sensing capability.