Abstract
Functions of III-nitride/ZnO heterostructures are attracting attention, and these heterostructures have been studied theoretically and experimentally with the aim of using them to fabricate optoelectronic devices composed of III-nitride/ZnO heterojunctions. The crystalline polarity of III-nitride and ZnO is another important issue in the development of optoelectronic devices fabricated using III-nitride and ZnO. Since a wurtzite-type structure lacks inversion symmetry, III-nitride and ZnO are permanently polarized along the c-axis of their lattice and exhibit pyroelectricity and piezoelectricity. Such polarization in III-V nitride semiconductors affects the properties of LEDs and transistors. III-nitride films were grown on the c-face of ZnO single crystals by molecular beam epitaxy, and their interfacial structure and polarity is discussed based on the structural similarity between the ZnO-based homologous structure and the III-nitride/ZnO interface.
