Growth and characterization of Metal assisted pecvd grown silicon Nanowires and their application in Radial junction thin film solar cells

Abstract

This thesis aims to synthesize, characterize, analyze and optimize the structural properties of SiNWs that are suitable for hydrogenated amorphous silicon (a-Si:H) based radial junction (RJ) solar cells application. SiNWs were grown using gold (Au), tin (Sn) and indium (In) metal catalyst by VLS mechanism in a controlled environment using a PECVD reactor. The structural properties of SiNWs depend on the PECVD process conditions and hence to achieve SiNWs with desired morphology, various process conditions such as substrate temperature, plasma power density, precursor gases flow rate, and thickness of metal catalyst layer, were optimized. newlineEven after five decades since its discovery of VLS mechanism by Wagner and Ellis, it is the most preferred mechanism used for the growth of nanowires (NWs). In their work, Au was used as the metal catalyst and growth was carried out at 950°C temperature. To establish the fundamental understanding of the VLS growth process of SiNWs by PECVD, we have selected Au as a catalyst. Apart from the more generalized Au catalyst, other metal catalysts of Sn and In are investigated for producing SiNWs at a lower process temperature, which is suitable for photovoltaic application. The present thesis is divided into seven chapters. newlineChapter 1 provides an overview of SiNWs as a potential choice of semiconducting material. We have reviewed the various fabrication methods of SiNWs, but the focus of discussion is on VLS growth by the PECVD method. This chapter also introduces the fundamentals of solar cells and the implementation of grown SiNWs in RJ solar photovoltaic for energy conversion. A brief literature review on the growth methodology adopted so far and their application in solar cells is given at the end of the chapter newline newline