Wavelength‐Dependent Bipolar Photoresponse Enabled All‐in‐One Optoelectronic Logic Gates on Epitaxial GaSe/GaN 2D‐3D Hybrid Heterojunctions

Abstract The growing demand for information processing and transmission requires high‐performance device platforms for efficient computing and telecommunications. Optoelectronic logic devices are promising candidates for next‐generation in‐sensor computing units, owing to their intrinsically high optical gain and transmission speed. However, reliable all‐in‐one optoelectronic logic gates that integrate all logical operations into a single device are still lacking. Herein, a new architecture is reported for an all‐in‐one device fabricated using a large‐scale epitaxial GaSe/GaN heterojunction. The functioning mechanism of such devices is based on the unique wavelength‐dependent bipolar photoresponse originating from the competition between the photovoltaic and photothermoelectric effects, which can be tuned by film thickness. GaSe films are epitaxially grown on a GaN substrate by physical vapor deposition in an ultrahigh‐vacuum environment, which guarantees an atomically clean interface. The device demonstrates superior optoelectronic performance with a detectivity of 4 × 10¹² Jones and an on‐off ratio of 4 × 10³. All seven logic gates, “AND,” “OR,” “NOT,” “XOR,” “NOR,” “XNOR,” and “NAND,” have been performed via all optical modulation within a single device. This study provides a novel approach for fabricating all‐in‐one multifunctional optoelectronic gates.