Bias-dependent Contact Resistance in Rubrene Single-Crystal Field-Effect Transistors

TL;DR

This study investigates how contact resistance in rubrene single-crystal FETs varies with bias and electrode material, revealing reproducibility in bias-dependent conductance that could aid microscopic carrier injection analysis.

Contribution

It provides a systematic analysis of bias-dependent contact resistance across different metals, highlighting reproducibility in differential conductance normalization.

Findings

Reproducibility varies significantly with electrode metal.

Ni, Co, and Cu contacts show consistent bias-dependent conductance.

Au contacts exhibit large variability in contact resistance.

Abstract

We report a systematic study of the bias-dependent contact resistance in rubrene single-crystal field-effect transistors with Ni, Co, Cu, Au, and Pt electrodes. We show that the reproducibility in the values of contact resistance strongly depends on the metal, ranging from a factor of two for Ni to more than three orders of magnitude for Au. Surprisingly, FETs with Ni, Co, and Cu contacts exhibits an unexpected reproducibility of the bias-dependent differential conductance of the contacts, once this has been normalized to the value measured at zero bias. This reproducibility may enable the study of microscopic carrier injection processes into organic semiconductors.