Epitaxial growth of ZnO nanorods on diamond and negative differential resistance of n-ZnO nanorod/p-diamond heterojunction

In this paper, we report the epitaxial growth of ZnO nanostructures on diamond by a thermal vapor transport method. Experimentally, the [0 0 0 1]-oriented ZnO nanorods (NRs) are generally vertically (inclined) grown on diamond (1 1 1) ((1 0 0)) facets. The epitaxial relation between the (0 0 0 1) ZnO and (1 1 1) diamond is proposed following image or image, while the relation between the (0 0 0 1) ZnO and (1 0 0) diamond is mainly of (0 0 0 1)[0 0 0 1]ZnO//(1 0 1)[1 0 1] diamond. The n-ZnO NR/p-diamond heterojunctions are constructed and show typical rectifying current–voltage behavior for lightly boron-doped p-type diamond. A negative differential resistance (NDR) phenomenon is presented for the heterojunctions when the p-type diamond is degenerated by heavily doping with boron. The origin of the NDR is attributed to the tunneling current occurred in the hybrid structures.