硫化锌与硫化锌/氧化锌异质结纳米线的化学气相沉积法制备与表征

介绍一种利用石墨还原快速制备大量硫化锌纳米线的方法,并分别合成了超晶格型、双轴型、核/壳型的硫化锌/氧化锌异质结纳米线。所合成的硫化锌纳米线存在六方纤锌矿和立方闪锌矿两种晶型,纳米线长度达几十微米,直径在20-50 nm,直径均匀且产量很高。在具有双轴型的硫化锌/氧化锌异质结中,首次发现具有超结构特征的氧化锌。HRTEM分析表明,硫化锌/氧化锌超晶格异质结界面为ZB-ZnS(111)∥ZnO(0001),而核/壳型异质结界面为W-ZnS(0001)∥ZnO(0001),这三个晶面分别为各自晶体的极性面,即所合成的硫化锌/氧化锌异质结中极性面相互平行。对ZnS 和ZnS/ZnO 异质结的生长机制进行了探讨,并对硫化锌纳米线与硫化锌/氧化锌异质结的光学性质进行了分析。

Preparation and Characterization of ZnS and ZnS/ZnO Heterostructure Nanowire by Chemical Vapor Deposition

This paper presents a rapid preparation of large amounts of ZnS nanowires and ZnS/ZnO heterostructure nanowires by chemical vapor deposition based on graphite reduction.The mixtures of ZnS and graphite powder with mass ratio of 3∶1 were placed in a quartz boat,and the quartz boat was positioned at the center of a quartz tube furnace.A Si substrate coated with gold nanoparticles was placed at 5 cm downstream of carrying gas flow from ZnS source.Under a constant nitrogen flow rate of 100 mL/min,the furnace was elevated to 870～935 ℃ at a pressure of 2000～2666 Pa.After reaction for 5～30 min,the Si substrate was taken out of the furnace after it was cooled down to room temperature,and the ZnS nanowires were grown on the substrate.Moreover,the superlattice and biaxial ZnS/ZnO heterostructure nanowires can be produced using the mixtures of ZnS,ZnO,and graphite with mass ratio of 1.5∶1.5∶1 as raw materials with a reaction temperature of 935～970 ℃.The cable-like ZnS/ZnO heterostructure nanowires can be obtained by annealing the obtained ZnS nanowires in nitrogen at 700 ℃ for 2 h.The as-grown products have been characterized by X-ray diffraction,scanning electron microscopy,high-resolution transmission electron microscopy,and photoluminescence.The as-grown ZnS nanowires contain Wurtzite and Zinc blende structures,and the nanowires are tens of micrometers in length and 20～50 nm in diameter with high yield.To the best of our knowledge,it is the first report concerning the ZnO superstructure found in the as-gown biaxial ZnS/ZnO heterostructures.The HRTEM analysis shows ZB-ZnS(111)//ZnO(0001) in the superlattice heterojunctions and W-ZnS(0001)//ZnO(0001) in the cable-like heterojunctions.The three crystal planes are all polar planes,and they are parallel to each other in the ZnS/ZnO heterojunctions.The growth mechanism of ZnS and ZnS/ZnO heterostructure nanowires has been discussed.Their photoluminescence properties have been analyzed,and they all show broad green emission band.