Low-temperature vapor–solid growth and excellent field emission performance of highly oriented SnO2 nanorod arrays

Well-aligned SnO2 nanorod arrays were grown directly on a single-crystalline Si, conductive and quartz glass substrates by thermal evaporation of a mixture of stannous chloride dihydrate (SnCl2·2H2O) and anhydrous zinc chloride (ZnCl2) powders at 600 °C in air. The SnO2 nanorod is a single crystalline with a tetragonal structure and grows along the [0 0 1] direction. A single-layer SnO2 nanoparticle film is first formed via the vapor–solid (VS) process based on the decentralization function of ZnCl2 vapor in the reaction chamber. The SnO2 nanoparticles served as seeds, and grew into nanorod arrays via the VS process. The density of the nanorods can be changed by adjusting the weight ratio of ZnCl2 to SnCl2·2H2O in the mixture. The field emission properties of the SnO2 nanorod arrays were measured, and exhibited a turn-on field of 1.67 V μm−1 and a field-enhancement factor of 2866. Moreover, this low-temperature VS growing process may be employed for the synthesis of highly oriented nanorod arrays of other oxides, and provides opportunities for both fundamental research and technological applications.