Unipolar Field-Effect Diode Based on a Complex Oxide*

We demonstrate rectifying behavior in a field-effect device structure fabricated from thin NdNiO$_{3}$ films grown on SrTiO$_{3}$ substrates by the pulsed laser deposition technique. In contrast to the conventional three-terminal field effect devices, the device has only two terminals with the field gate electrode connected to one of the terminal electrodes. The active device area is a $10\mu$m$\times$$10\mu$m square with a Au/Al$_{2}$O$_{3}$/NdNiO$_{3}$/SrTiO$_{3}$ structure, where Au and Al$_{2}$O$_{3}$ are the gate and the gate insulator, respectively. At small bias voltages, the device exhibits a metal-insulator transition near T=150K, similar to extended NdNiO$_{3}$ films. I-V measurements reveal a strong dependence of device characteristics on temperature, applied bias, and both thermal and applied bias histories. We analyze the IV characteristics by using a modified charge-control model based on accumulation of charges in the channel near the gate oxide interface. We deduce the temperature dependence of the effective zero-field charge carrier mobility for the channel by including a field-dependence mobility. The observed hysteretic effects can be utilized in complex oxide devices that combine together both the diode and the memory functionalities.