  Using the metal-insulator transition that takes place as a function of
carrier density at the LaAlO$_3$-SrTiO$_3$ interface, oxide diodes have been
fabricated with room-temperature breakdown voltages of up to 200 V. With
applied voltage, the capacitance of the diodes changes by a factor of 150. The
diodes are robust and operate at temperatures up to 270 C.
