In situ formation of indium catalysts to synthesize crystalline silicon nanowires on flexible stainless steel substrates by PECVD

Abstract

Intrinsic and n-type silicon nanowires were synthesized on flexible stainless steel substrates by plasma-enhanced chemical vapor deposition. Indium nanoparticles fabricated by hydrogen plasma treatment on flexible stainless steel substrates were used as metal catalysts. The differences between intrinsic and n-type silicon nanowires were investigated. The crystal structure of the nanowires was characterized by electron microscopy and X-ray diffraction. It is shown that the as-synthesized silicon nanowires were single crystals and the intrinsic silicon nanowires had better morphology and tended to have higher concentration twin crystals than the n-type silicon nanowires. The phosphorus atom percentage of the n-type silicon nanowires was 2.17% as determined by energy dispersive spectroscopy. The SiNWs on the glass substrates has lower reflectance than the SiNWs on the flexible stainless steel substrates in the range 750–1100 nm wavelengths.

Introduction

One-dimensional nanostructured materials and ordered nanomaterial arrays have attracted great interest in the recent years due to their novel chemical and physical properties [1], [2], [3] for future use in improving the performance of electronic devices [4], [5], [6], [7] while silicon nanowire (SiNW) arrays have shown a great potential to fabricate high efficiency and cost-effective solar cells because of their excellent optical and electrical properties [8], [9], [10], [11], [12].

Vapor–liquid–solid (VLS) [13] growth is the most common method used for the synthesis of SiNWs. Among all the methods of synthesizing SiNWs by VLS, the route where SiNWs are synthesized in situ after hydrogen plasma treatment on TCO/glass substrates by plasma-enhanced chemical vapor deposition (PECVD) has very great attractiveness for its several advantages: low temperature, large area and no Au contamination. Alet et al. [14] and Jeon and Kamisako. [15] have reported some valuable results about this route. But they focused only on glass substrates and little work has been done on synthesizing SiNWs on flexible substrates. The flexible stainless steel substrate can be a natural electrode. Thus, forming SiNWs on flexible stainless steel is attractive for photovoltage and stored energy devices such as solar cells and lithium battery. In this paper, in situ formation of indium catalysts and subsequent synthesis of crystalline SiNWs on flexible stainless steel substrates by PECVD are reported. The characteristics of the synthesized SiNWs were analyzed and discussed.