Study of large area hydrogenated microcrystalline silicon p-layers for back surface field in crystalline silicon solar cells

Abstract

A series of hydrogenated microcrystalline silicon (μc-Si:H) p-layers for back surface field in crystalline silicon solar cells were deposited on glass substrates by the developed large area (45 cm×45 cm) plasma enhanced chemical vapour deposition processor operating at 13.56 MHz and various values of source gas trimethylboron (TMB) to H2 flowratio. The influence of deposition parameters on the large area p-layer performance was intensively studied, as well as the thin film uniformity, optical, electrical and structural performances by Raman, FTIR, Ellipsometry, etc. Arrhenius and Tauc plots were used to discuss the μc-Si:H thin film’s activation energy and the defects state distribution. When amorphous-microcrystalline transition state was obtained, the deposited p-doped μc-Si:H layers showed specific resistance of 38.3 Ω−1cm−1 at the flowratio of 0.66% and high crystallinity of 45%–50% with no further treatment. The effect of source gas flowratio, deposition rate, and source gas partial pressure on μc-Si:H thin film’s performance was also investigated.