Eur. Phys. J. Special Topics 222, 1057-1063 (2013)
https://doi.org/10.1140/epjst/e2013-01906-0

Regular Article

Critical behavior of a filling-controlled Mott-transition observed at an organic field-effect-transistor interface

¹ CIMoS, Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan
² Advanced Science Institute, RIKEN, Wako, Saitama, 351-0198, Japan
³ JST-PRESTO, Kawaguchi, Saitama 332-0012, Japan

Received: 18 March 2013
Revised: 12 May 2013
Published online: 15 July 2013

Abstract

An organic Mott-insulator κ-(BEDT-TTF)₂Cu[N(CN)₂] Cl(κ-Cl) on SiO₂/Si substrate showed an ambipolar field-effect-transistor (FET) characteristics without any hysteresis, which means a continuous Mott-transition at filling-controlled regime (BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene). In order to extract the critical exponent in the vicinity of the Mott-insulating phase, an analysis based on Efros-Shklovskii approximation is performed. The model fitting well reproduces the device characteristics over wide range of temperature and gate voltage. In this analysis, Coulomb gap temperature that characterizes the ground state of doped Mott-insulator shows inversely proportional critical behavior against the doping concentration.