なかのにっき

The ZnO nanopencils were synthesized via a two-step pressure controlled vapor phase deposition. A n-type silicon wafer and zinc powders were inserted into a horizontal quartz tube. Different from conventional thermal evaporation, neither tedious catalysts nor additives are needed. A 1 mm gap was set between the sources and the substrate. During the experiments, the sources were heated at a rate of 20 ℃/min from room temperature carried in by argon with a flow rate of 54 sccm. Once the temperature was raised to 450 ° C, oxygen was introduced into the chamber with a flow rate of 3 sccm. The working pressure was kept at 15 Torr. After heating at 550 ℃ for 30 min, the substrate was slowly cooled down in furnace and the working pressure was decreased from 15 to 5 Torr. After the substrate was cooled to room temperature, the Si wafer was covered with a whitecolored semitransparent film.