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One of the promising future ways of computing is using principles similar to the human brain work mechanism. Neuromorphic photonics makes it possible to create computational elements with properties similar to the principles of the biological synapse. Neuromorphic computers can overcome the von Neumann bottleneck fundamental limitation of existing computing systems.
In a current study, we demonstrate a neuromorphic properties, observing on photoconductive structures based on nanocrystalline ZnO, WO3, In2O3 triggered by presynaptic light spikes with the 405nm wavelength. Photoconductive structures based on ZnO, WO3, In2O3 were deposited as a 100–200 nm thick film on the surface of the chip.
Excitatory post-synaptic current value was measured for different excitation pulse durations. The excitatory post-synaptic current caused by a pair of presynaptic light spikes was studied for different delay times between pulses. The ability of these structures to act as biological synapses like high-pass temporal filtering function was demonstrated by measuring post-synaptic current when exposed to a series of 30 consecutive presynaptic light spikes.
Our photoconductive semiconductor structures have two different relaxation mechanisms. Due to this, the structures possess short-term and long-term photoconductivity memory. To demonstrate the ability of our samples possesses long-term memory, we studied the semiconductor photoconductivity relaxation values after light exposure during 500 seconds. The memory level after light exposure were stored over an hour.
The studied photoconductive structures showed the presence of a spike reaction properties, the effect of amplitude and frequency filtering, short-term and long-term memory, and they are looking promising for use as elements of neuromorphic photonics.
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