Heteroepitaxy of ε‐Ga2O3 thin film for artificial synaptic device

Abstract

AbstractEmerging‐wide bandgap semiconductor Ga2O3 shows distinct characteristics for optoelectronic applications and a stable crystal phase of Ga2O3 is highly desired. Herein, we have first reported a metal‐semiconductor‐metal structure photonic synaptic device based on the ε‐Ga2O3 thin film. The ε‐Ga2O3 epilayer is grown on the c‐sapphire with a low temperature nucleation layer, which presents a crystal orientation relationship with the c‐sapphire (ε‐Ga2O3 <010> // c‐sapphire <1–100> and ε‐Ga2O3 <001> // c‐sapphire <0001>). The ε‐Ga2O3 photonic device was stimulated by UV pulses at different pulse widths, pulse intervals, and reading voltages. Under the UV pulse excitation, the photonic device exhibits primary synaptic functions including excitatory postsynaptic current, short term memory, pair pulse facilitation, long term memory, and STM‐to‐LTM conversion. In addition, stronger and repeated stimuli can naturally contribute to the higher learning capability, thus prolonging the memory time.