Limit of Field Effect Mobility on Pentacene Single Crystal

TL;DR

This study fabricates and characterizes single-crystal pentacene FETs, revealing high hole mobility and insights into the intrinsic free carrier mobility, with implications for organic semiconductor performance.

Contribution

It provides the first detailed measurement of the intrinsic free carrier mobility in single-crystal pentacene FETs, highlighting the impact of gate voltage on activation energy and carrier dynamics.

Findings

Room temperature effective mobility up to 0.30 cm2/Vs

On/off ratio up to 5×10^6

Intrinsic free carrier mobility approximately 75 cm2/Vs

Abstract

We report on fabrication and characterization of field effect transistors (FETs) on single-crystal pentacene. These FETs exhibit hole conductivity with room temperature effective mobility up to 0.30 cm2/Vs and on/off ratios up to 5*10^6. A negative gate voltage of -50V significantly decreases the activation energy (Ea) down to 0.143 eV near room temperature. Assuming thermal equilibrium between trapped and free carriers, from Ea = 0.143eV, we find the number of free carriers is only 0.4% of the total number of injected carriers. Along with effective mobility ~ 0.3 cm2/Vs this gives the intrinsic free carrier mobility of ~75 cm2/Vs.