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

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, n(S), of 10(14) cm(-2), the electrochemical process causes persistent conduction even after removal of the gate bias above 3.75 V. n(S) reached 10(15) cm(-2) at 5 V, and the electron mobility at 2 K was as large as 10(4) cm(2)/V s. This persistent conduction originates from defect formation within a few micrometers depth of SrTiO3. (C) 2010 American Institute of Physics. [doi:10.1063/1.3457785]