Chemical vapor deposition of Ge nanowires from readily available GeO2 and CH4 precursors

Abstract

The present study aimed to investigate growth of Ge nanowires on a Si substrate by chemical vapor deposition technique at atmospheric pressure using readily available precursors GeO2 and CH4. The process consists of two consecutive steps: generation of gaseous GeO and growth of Ge wires. The species was in-situ produced at 1100 K by the reactions between GeO2 and CH4 pyrolysis products. It was transported by the main gas flow to the Au-coated Si substrate heated to 1073 K and to 723 K. At 1073 K, large droplets and thick Ge wires were observed on the substrate. Ge nanowires with high aspect ratios were obtained at 723 K. Growth of Ge wires from the GeO2 and CH4 derived species was discussed in terms of vapor-liquid-solid mechanism and the reduction reactions.