Orientation-engineered β-Ga2O3 optoelectronic synapses for polarization-sensitive neuromorphic vision

Abstract

Polarization-sensitive neuromorphic visual systems offer a promising route for extracting optical information, yet their practical miniaturization and integration remain limited by the reliance on bulky optical components and separated processing units. Here, we demonstrate an orientation-engineered β-Ga₂O₃ ultraviolet optoelectronic synapse for polarization-sensitive neuromorphic vision. Based on Fermi's golden rule and optical transition selection rules, the (201) plane of β-Ga₂O₃ is theoretically revealed to exhibit stronger polarization-selective absorption, with a dichroic ratio of 3.2 at 258 nm. (201)-oriented β-Ga₂O₃ epitaxial films are controllably grown on r-plane sapphire substrates through substrate engineering. The device successfully emulates essential polarization sensitivity synaptic functions, including short-term to long-term memory transition, with stronger learning and memory capability. Furthermore, the polarization-modulated synaptic response is exploited for reservoir-computing-based face recognition, achieving 92% accuracy after 200 training iterations under 0^° polarization. Device-derived polarization-modulated convolution kernels are also constructed for image edge enhancement and handwritten digit recognition, maintaining high accuracies of 99%, 99%, and 97% under 10%, 20%, and 50% noise, respectively. This work provides a strategy for β-Ga₂O₃-based polarization-sensitive optoelectronic synapses and offers a promising way for compact ultraviolet neuromorphic visual systems with integrated sensing, memory, and computing functionalities.