GaN Optoelectronic Integrated Chip with Multifunctions of Communication and Neuromorphic Computing

The ultimate neuromorphic chip based on light‐stimulated artificial synapses requires suitable materials and platforms for optoelectronic integration. Herein, a GaN optoelectronic integrated chip with multifunctions of communication, sensing, and neuromorphic computing is proposed and fabricated on a GaN‐on‐Si light‐emitting diode (LED) epitaxial wafer. The monolithically integrated chip consists of an InGaN/GaN multiple‐quantum‐well LED and a GaN‐based optoelectronic synaptic metal‐oxide‐semiconductor field‐effect transistor connected in series. It can achieve multi‐mode switching, including self‐powered photodetector (PD), light‐emitting synapse, and gate‐voltage‐controlled light transmitter. For the PD mode, a great responsivity of 4393 A W⁻¹ and a high specific detectivity of 1.56 × 10¹⁴ Jones are demonstrated. Notably, due to varying absorption of short wavelength light by different epitaxial layers, the integrated device shows differentiated wavelength selectivity for light illuminated from the front and back sides. When the integrated device is operating in synapse mode, excitatory postsynaptic currents induced by light stimuli can be read both optically and electrically with the assistance of built‐in optical‐to‐electrical‐to‐optical conversion. Moreover, direct bias‐voltage modulation and gate‐voltage modulation are both configured into this integrated device, achieving 60 and 5 Mbps modulation rates for visible light communication applications, respectively.