Micro Raman Spectroscopy Analysis of Doped Amorphous and Microcrystalline Silicon Thin Film Layers and its Application in Heterojunction Silicon Wafer Solar Cells

Abstract

Hydrogenated p+ and n+ doped silicon thin films deposited using radio frequency (13.56 MHz) plasma-enhanced chemical vapour deposition (PECVD) are studied in detail using micro Raman spectroscopy to investigate the impact of doping gas flow, hydrogen dilution ratio, film thickness, and substrate type on the doped silicon thin film characteristics. In particular, by deconvoluting the micro Raman spectra into amorphous and crystalline components, quantitative and qualitative information on bond angle disorder, bond length, nature of film stress, and film crystallinity can be extracted and used to predict the performance of these doped silicon thin films in heterojunction silicon wafer solar cells. By applying optimised doped silicon thin film deposition conditions to our heterojunction carrier lifetime structures and cell structures, we demonstrate an efficient field-effect passivation from these doped layers with improvement in implied open-circuit voltage and effective minority carrier lifetimes across the injection levels of interest. In particular, the device relevant heterojunction carrier lifetime structure