  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.
