Temperature-dependent contact resistances in high-quality polymer field-effect transistors

TL;DR

This study measures how contact resistance in P3HT organic transistors varies with temperature, revealing that contact effects diminish at lower temperatures and enabling more accurate mobility assessments.

Contribution

It provides detailed temperature-dependent measurements of contact and channel resistances in P3HT transistors, validating a recent contact resistance model.

Findings

Contact resistance decreases relative to channel resistance at lower temperatures.

Corrected mobilities can reach approximately 1 cm²/Vs at room temperature.

The ratio of contact to channel resistance depends on temperature and gate voltage.

Abstract

Contact resistances between organic semiconductors and metals can dominate the transport properties of electronic devices incorporating such materials. We report measurements of the parasitic contact resistance and the true channel resistance in bottom contact poly(3-hexylthiophene) (P3HT) field-effect transistors with channel lengths from 400 nm up to 40 $\mu$m, from room temperature down to 77 K. For fixed gate voltage, the ratio of contact to channel resistance decreases with decreasing temperature. We compare this result with a recent model for metal-organic semiconductor contacts. Mobilities corrected for this contact resistance can approach 1 cm$^{2}$/Vs at room temperature and high gate voltages.