Simulation on Junctionless Silicon Nanowire Devices for Implementation of Photodetection Circuit in Retinal Prosthesis

Abstract

Semiconductor nanowires have been studied owing to their excellent electrical properties. To implement an integrated system based on nanowires, well-aligned arrays of a nanowire are required for scalable and repeatable fabrication. In our previous results, a comparative study based on the current conduction mechanism of junctionless silicon nanowires was performed, and their characteristics were analyzed to offer a design guideline. Also, to implement a silicon-nanowire-based device, a top-down, wafer-level fabrication process of silicon-nanowire arrays on a flexible substrate was reported. The fabricated device consists of a voltage divider and a current driver in which silicon nanowires are used as a photodetector (PD) and fieldeffect transistors (FETs). The implemented silicon-nanowire-based circuit detects external light, generating a stimulation signal in proportion to the light intensity and transmitting the signal to a microelectrode. In this study, an analytical model based on a conduction mechanism of junctionless silicon nanowires is verified using a three-dimensional device simulator. Also, by applying the extracted electrical parameters of silicon-nanowire-based devices, the proposed photodetection circuit is simulated for the implementation of a photosensitive retinal prosthetic device. The results of this study can be applied to address novel silicon-nanowire-based neural stimulation devices and to guide the design of a high-resolution retinal prosthetic system.