Electric-Field Modulation of Thermopower for the KTaO3 Field Effect Transistors

TL;DR

This paper demonstrates the fabrication of KTaO3-based FETs with significant modulation of thermopower via electric fields, revealing insights into carrier effective mass differences compared to SrTiO3.

Contribution

It introduces a novel KTaO3 FET with higher mobility and demonstrates electric-field control of thermopower, advancing thermoelectric device research.

Findings

KTaO3 FET exhibits ~8 cm²/Vs mobility

Thermopower decreases from 600 to 220 μV/K under electric field

KTaO3 has smaller carrier effective mass than SrTiO3

Abstract

We show herein fabrication and field-modulated thermopower for KTaO3 single-crystal based field-effect transistors (FETs). The KTaO3 FET exhibits field effect mobility of ~8 cm2/Vs, which is ~4 times larger than that of SrTiO3 FETs. The thermopower of the KTaO3 FET decreased from 600 to 220 microV/K by the application of gate electric field up to 1.5 MV/cm, ~400 microV/K below that of an SrTiO3 FET, clearly reflecting the smaller carrier effective mass of KTaO3.