SWCNT-Si Photodetector with Voltage-Dependent Active Surface

Abstract

New works on Carbon Nanotubes-Silicon MIS heterostructures showed that the presence of thickness inhomogeneities in the insulating layer across the device can be exploited increase its functionalities. In this work, we report the fabrication and the characterization of a device consisting of a Single-Walled Carbon Nanotube (SWCNT) film onto an n-type silicon substrate where the nitride interlayer between the nanotubes and the silicon has been intentionally etched to obtain different thickness. Three different silicon nitride thicknesses allow the formation of three regions, inside the same device, each with different photocurrents and responsivity behaviors. We show that by selecting specific biases, the photoresponse of the regions can be switched on and off. This peculiar behavior allows the device to be used as a photodetector with a voltage dependent active surface. Scanning photo response imaging of the device surface, performed at different biases highlight this behavior.