Growth and characterization of ZnO nanowires grown on the Si(1 1 1) and Si(1 0 0) substrates: Optical properties and biaxial stress of nanowires

In this paper the effects of silicon substrates with different orientations on the morphological and optical properties as well as biaxial stress of ZnO nanowires were investigated. The ZnO nanowires were grown on Si(1 0 0) and Si(1 1 1) substrates by the vapor–solid (VS) method using a physical vapor deposition reactor. In addition ZnO nanowires were grown on Si(1 1 1) substrate by the vapor–liquid–solid (VLS) method using an Au film as catalyst, which were deposited on Si(1 1 1) substrate using a sputtering method, with the same conditions. Room temperature photoluminescence (PL) spectrum showed a stronger ultraviolet (UV) peak at 381 nm for the nanowires that were grown on Si(1 1 1) by the VS method than those that were grown on Si(1 0 0) with the same green emission (deep-level emission (DLE)) intensities at about 520 nm peak. On the other hand, the PL result of the ZnO nanowires, which were grown by the VLS method, showed the same intensities for the both UV and DLE peaks. Furthermore, the effects of silicon substrate orientation and Au catalyst on biaxial stress of the nanowires were studied by Raman spectrometer. It was discussed that Au catalyst was one of the important factors that could affect the biaxial stress value of the ZnO nanowires that were grown on Si substrates.