Microstructure and electrical properties of p-type phosphorus-doped ZnO films

The microscopic defects and their effects on the electrical properties of phosphorus-doped ZnO films epitaxially grown on (0 0 0 1) sapphire and ZnO substrates by pulsed laser deposition are studied. While threading dislocations were observed only in heteroepitaxial films, a high density of partial dislocations associated with interstitial dislocation loops was observed in films grown on both substrates. These dislocations provide sinks to quench native donors and favour the injection of zinc vacancies to form acceptor-complex defects, thus leading to p-type conductivity.