  We report on experimental realization of p-n heterojunctions based on p-type
GaN, and an n-type correlated oxide, VO2. The band offsets are evaluated by
current-voltage and capacitance voltage measurements at various temperatures. A
band diagram based on the conventional band bending picture is proposed to
explain the evolution of the apparent barier height from electrical
measurements and it suggests that the work function of VO2 decreases by ~0.2 eV
when it goes through the insulator to metal transtion, in qualitative agreement
with Kelvin force microscopy measurements reported in literature. The frequency
dependent capacitance measurements allows us to differentiate the miniority
carrier effect from the interface states and series resistance contributions,
and estimate the minority carrier lifetime in insulating phase of VO2 to be of
the order of few microseconds. The nitride-oxide based p-n heterojunctions
provide a new dimension
