Synaptic devices based on flash memory using quantum dots

Abstract

Neurons in the human brain exchange signals with each other through synapses, synapses transmit neurons’ information and represent various associations. In this study, the devices using quantum dots (QDs) were fabricated and presented as a synaptic mimic device. A programming/erasing process was performed to insert or remove electrons from the quantum dots by applying a gate voltage to the electrode of the device having a stack structure of Pt/Cr/Al₂O₃/QDs/Al₂O₃/SiO₂/Si. To use as a synaptic mimetic devices, analog characteristics that can express various levels of connection strength, repeatability, reproducibility, and retention are required. Therefore, the number of electrons stored in the quantum dots was adjusted by changing the applied voltage and time, and the synaptic characteristics of the device in various stages were confirmed. The state of the device was expressed through the flatband voltage shift by measuring the capacitance–voltage characteristic curves. In addition, it was observed that the device continued to operate when programming/erasing was repeated, and it was confirmed that the device’s state was maintained over time.