Observation of a Large Photo-response in a Single Nanowire (Diameter ~30 nm) of Charge Transfer Complex Cu:TCNQ

TL;DR

This study demonstrates a significant photoresponse in a single Cu:TCNQ nanowire, revealing potential for nanoscale optoelectronic applications through detailed analysis of photocurrent mechanisms.

Contribution

First observation of large photoresponse in a single Cu:TCNQ nanowire device with detailed modeling of photocurrent behavior.

Findings

Large photocurrent observed at zero bias.

Photoresponse peaks at ~405 nm wavelength.

Bias reduces nanowire resistance and contact barriers.

Abstract

We report for the first time large photoresponse in a single NW of the charge transfer complex Cu:TCNQ. We fabricate a metal-semiconductor-metal device with a single NW and focus ion beam deposited Pt. We observe large photocurrent even at zero bias. The spectral dependence of the photoresponse follows the main absorption at ~ 405 nm which has the primarily responsible for photogenerated carriers. We have quantitatively analyzed the bias dependent photocurrent by a model of two back to back Schottky diodes connected by a series resistance. The observation shows that the large photoresponse of the device primarily occurs due to the reduction of the barrier at the contact regions due to illumination along with the photoconductive contribution. There is also a bias driven reduction of the nanowire resistance that is a unique feature for the material.