GaN / VO2 heteroepitaxial p-n junctions: Band offset and minority carrier dynamics

TL;DR

This study experimentally investigates GaN/VO2 heterojunctions, analyzing band offsets and minority carrier dynamics, revealing a decrease in VO2 work function during phase transition and estimating minority carrier lifetime.

Contribution

It provides the first detailed analysis of band offsets and minority carrier behavior in GaN/VO2 heterojunctions, highlighting phase transition effects.

Findings

VO2 work function decreases by ~0.2 eV during insulator-metal transition

Minority carrier lifetime in VO2's insulating phase is a few microseconds

Band diagram explains evolution of barrier height with temperature

Abstract

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