An in situ transport measurement of interfaces between SrTiO3(1 0 0) surface and an amorphous wide-gap insulator

We have explored the transport properties of the interface between a SrTiO3(1 0 0) single crystal and a CaHfO3 wide-gap insulator layer deposited by pulsed laser deposition. The electrical transport measurements were done in situ during the heterojunction fabrication and consistently showed an enhancement of interface conductivity. A conducting interface was always obtained, independent of deposition parameters (laser pulse rate, laser fluence, oxygen pressure, and substrate termination). The conduction was attributed to plume-induced photocurrent in SrTiO3. The current decay rate after insulator film fabrication was strongly influenced by substrate termination. An exponential relaxation-type photocurrent decay was clearly seen on SrO-termination, whereas a nearly constant conductivity was seen for up to 24 h on TiO2-terminated surfaces.