  Transport properties have been studied for a perovskite heterojunction
consisting of SrRuO$_{3}$ (SRO) film epitaxially grown on
SrTi$_{0.99}$Nb$_{0.01}$O$_{3}$ (Nb:STO) substrate. The SRO/Nb:STO interface
exhibits rectifying current-voltage ($I$-$V$) characteristics agreeing with
those of a Schottky junction composed of a deep work-function metal (SRO) and
an $n$-type semiconductor (Nb:STO). A hysteresis appears in the $I$-$V$
characteristics, where high resistance and low resistance states are induced by
reverse and forward bias stresses, respectively. The resistance switching is
also triggered by applying short voltage pulses of 1 $\mu$s - 10 ms duration.
