1/f Tunnel Current Noise through Si-bound Alkyl Monolayers

TL;DR

This study investigates low-frequency noise in Si-bound alkyl monolayer tunnel junctions, revealing a 1/f^y power spectrum influenced by bias and trap states, supported by a qualitative model.

Contribution

It provides the first detailed analysis of 1/f tunnel current noise in organic monolayer junctions, linking noise behavior to trap-induced tunneling effects and proposing a supporting model.

Findings

Noise exhibits a 1/f^y power spectrum with y between 1 and 1.2.

Background noise scales with the square of the differential conductance.

Bias-dependent local noise increases are linked to trap states.

Abstract

We report low frequency tunnel current noise characteristics of an organic monolayer tunnel junction. The measured devices, n-Si/alkyl chain (C18H37)/Al junctions, exhibit a clear 1/ f^y power spectrum noise with 1< y <1.2. We observe a slight bias dependent background of the normalized current noise power spectrum (SI/I^2). However, a local increase is also observed over a certain bias range, mainly if V > 0.4 V, with an amplitude varying from device to device. We attribute this effect to an energy-dependent trap-induced tunnel current. We find that the background noise, SI, scales with (\partial I/\partial V)^2 . A model is proposed showing qualitative agreements with our experimental data.