Realization of nitride–oxide based p–n heterojunctions with the n-VO2/p-GaN/sapphire structure

• The n-VO2/p-GaN/sapphire based nitride–oxide p–n heterojunctions was realized.
• The optimized sample exhibit distinct reversible SMT transition characteristics.
• Clear rectifying I–V character were observed before and after SMT of VO2 layer.
• The crystallinity of p-GaN under layer did not degrade at any detectable level.
• The mechanism for the observed I–V character was clarified.

The nitride–oxide based p–n heterojunctions with the n-VO2/p-GaN/sapphire structure was realized by sputtering deposition of VO2 films on p-GaN/sapphire substrates. The structure and electrical properties of the as-grown VO2/p-GaN/sapphire heterostructure were investigated systematically. The distinct reversible semiconductor-to-metal transition (SMT) with resistance change up to nearly two orders of magnitude was observed for the sample deposited at the optimized conditions. Moreover, the clear rectifying current–voltage characteristics originated from the n-VO2/p-GaN interface were demonstrated both before and after SMT of VO2 over layer, which were attributed to the p–n junction behavior and Schottky contact character, respectively. Our present finding demonstrated the feasibility of integrating correlated oxide and wide bandgap nitride semiconductors, and will further motivate research in novel devices with combined functional properties of both kinds of materials.

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