Selective Growth and Directed Integration of ZnO Nanobridge Devices on Si Substrates without a Metal Catalyst Using a ZnO Seed Layer

Directed assembly and integration of ZnO nanobridges (NBs) into working devices on Si substrates was achieved. Metal catalysts were not used, and the ‘‘harvest and disperse’’ method of nanorod (NR) integration was avoided. High-quality ZnO NRs were grown via a vapor–solid method selectively on a patterned thin-film ZnO seed layer. ZnO NRs exhibited a single-crystalline structure with c-axis preferred orientation, were aligned roughly perpendicular to the surface, and showed a strong intrinsic near-band edge photoluminescence peak at 380 nm with no detectable visible photoluminescence. These ZnO NRs were grown to span gaps between separated electrodes, terminate on an opposing surface, and effectively form electrically accessible vertical or horizontal ZnO NB devices. Operation of the directly grown horizontal ZnO NB devices as gas and UV sensors was performed, demonstrating a significant step toward practical large-scale integration of nanodevices into Si microelectronics.