Effect of synthesis conditions on the morphology and field-emission properties of hydrothermally grown Zn-doped SnO2 nanorods

Abstract

Zn-Doped SnO₂ (Zn–SnO₂) nanorod arrays with different morphologies have been directly grown on a copper substrate by a simple organic-free hydrothermal process. The effect of synthesis conditions including the Zn⁺ concentration and ethanol volume ratio in the solvent on the morphology and field emission (FE) properties of Zn–SnO₂ was investigated. It was found that the aspect ratio of the products increases with the increase of Zn⁺ concentration. The ethanol-to-water ratio also played an important role in the shaping morphology of Zn–SnO₂. Under the optimized hydrothermal conditions, sword-like Zn–SnO₂ nanorods with the highest aspect ratio (∼11.25) were obtained. Moreover, the sword-like nanorods possess the best FE properties, including the lowest turn-on field of ∼2.75 V μm⁻¹, the highest field-enhancement factor of ∼1970 and excellent stability with fluctuations within 11%. These results are attributed to the sturdy structure of the sword-like nanorods as well as the fortified junction formed between the emitter and the highly conductive copper substrate interface.