| 초록 |
We reported on the formation mechanism of ZnS nanosheets based upon extensive scanning electron microscopy and transmission electron microscopy experiment. ZnS nanostructures commonly have various kinds of morphology involving nanowires, nanobelts, nanosheets, and the morphology was varied by changes in the reaction temperatures and duration. We observed that most of the ZnS nanowires having two types of [0001] and [0-110] growth direction for the formation the nanowires. The nanowire grown along [0001] direction showed unidirectional growing behavior irrespective of reaction temperature and duration. In contrary to the former case, the nanowire grown along [0-110] showed not only axial growth behavior but lateral growth behavior, which is mainly due to the vapor-liquid-solid (VLS) and vapor-solid (VS) growth mechanism in formation of the nanostructures simultaneously. We proposed a four-step process for the morphological evolution of ZnS nanowires to nanosheets; (1) nucleation and growth of nanowires by vapor-liquid-solid (VLS) mechanism, (2) growth of nanowires with axial direction and growth of side branches nanowires with undulated stem by vapor-solid (VS) mechanism simultaneously, (3) coalescence of neighbored branched nanowires followed by filling planar interspaces, and (4) formation of nanosheets. In the present study, each step was discussed focusing on its distinctive morphological characteristics. |
