Performance comparison of ZnO and ZnON based optoelectronic synapses

Herein, we present light driven optoelectronic artificial synapses based on ZnO and ZnON thin films and their performance comparison for potential applications in neuromorphic computing. The films respond to optical inputs utilizing the persistent photoconductivity of the material. A few synaptic functions of the human brain namely sensory memory, short-term memory, long-term memory, duration-time-dependent plasticity, and paired pulse facilitation have been demonstrated and compared. The ZnO synapse is able to deliver a PPF index of around 166%, while ZnON synapse delivers a PPF index of 140% in UV wavelength regime. For a pulse time interval of 10s, the PPF index values of ZnO synapse is 21.34% and 35.35% more than ZnON under UV and blue input respectively. A comparison of their performances shows that ZnO synapse offers a better synaptic performance than ZnON in various aspects such as rise in current, retention current, decay in current and PPF index values.