Electrostatic charge accumulation versus electrochemical doping in SrTiO3 electric double layer transistors

TL;DR

This study distinguishes between electrostatic and electrochemical effects in SrTiO3 electric double layer transistors, revealing how bias voltage influences charge accumulation, electrochemical reactions, and persistent conduction due to defect formation.

Contribution

It demonstrates the voltage-dependent transition from reversible electrostatic charge accumulation to irreversible electrochemical doping in SrTiO3 transistors, highlighting defect-related persistent conduction.

Findings

Electrostatic charge accumulation is reversible below 3.7 V.

Electrochemical doping causes persistent conduction above 3.75 V.

Electron mobility reaches 10^4 cm2/Vs at 2 K.

Abstract

In electric double layer transistors with SrTiO3 single crystals, we found distinct differences between electrostatic charge accumulation and electrochemical reaction depending on bias voltages. In contrast to the reversible electrostatic process below 3.7 V with a maximum sheet charge carrier density, nS, of 1014 cm-2, the electrochemical process causes persistent conduction even after removal of the gate bias above 3.75 V. nS reached 1015 cm-2 at 5 V, and the electron mobility at 2 K was as large as 104 cm2/Vs. This persistent conduction originates from defect formation within a few micrometers depth of SrTiO3.