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 (SnCl ₂·2H₂O) and anhydrous zinc chloride (ZnCl ₂) 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 ZnCl ₂ 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.