Large photoresponse of Cu:TCNQ nanowire arrays formed as aligned nanobridges

TL;DR

This paper demonstrates a highly responsive Cu:TCNQ nanowire array device with significant photoresponse, especially at 405 nm, showing potential for optoelectronic applications due to its high current gain and responsivity.

Contribution

First demonstration of large photoresponse in Cu:TCNQ nanowire arrays fabricated as nanobridge devices, with detailed analysis of photocurrent mechanisms.

Findings

Maximum current gain of ~10^4 at zero bias

Responsivity reaches 1.0 A/W at 2 V bias

Strong photoresponse at 405 nm matching absorption peak

Abstract

We report for the first time a large photoresponse in an array of charge transfer complex Cu:TCNQ nanowires (average diameter 30 nm) fabricated as a nanobridge device. The device shows highest photoresponse for excitation with 405 nm light which matches with its absorption peak. The current gain at zero bias can reach ~104 with an illumination power density of 2x106 W/m2. The zero bias responsivity is ~0.3 mA/W which increases on applying bias reaching 1.0 A/W or more for a bias of 2.0 Volt. Dark and illuminated I-V data are analyzed by two back-to-back Schottky diodes model, which shows the predominant photocurrent in the device arising from the photoconductive response of the nanowires.