Evaluation on the factors influencing thermal-stress-induced growth of Sn nanowires

By employing a multilayer thin film structure composed of thermally oxidized Si substrate and sputtered Sn film, a series of thermal annealing experiments are carried out to challenge the synthesis of Sn nanowires following thermal-stress-induced method. The effects of two vital influencing factors, i.e., surface morphology of Sn film and annealing conditions, are explored systematically. For Sn films with either isolated islands or voids in grain boundaries, there is no any change on surface morphology after annealing. Such behavior can be attributed to the existence of gaps among islands or voids in grain boundaries, which make it difficult to generate sufficient stress to grow Sn nanowire. On the other hand, for Sn films with dense grains or coalescent islands, the occurrence of hillocks or whiskers after annealing at high temperature indicates that the proper control of surface morphology of Sn film and thermal annealing conditions may grow Sn nanowires with large aspect ratio.