A chemical vapor deposited silicon rich silicon carbide P-N junction based thin-film photovoltaic solar cell

In contrast to silicon-based p-n junction photovoltaic solar cells (PVSCs), a silicon rich silicon carbide (SixC1-x)-based thin-film PVSC with enhanced absorption at the visible wavelength region. The silicon rich SixC1-x films are synthesized by using a lowsubstrate temperature and low-power plasma-enhanced chemical vapor (PECVD) system in a silane-rich environment. The molar ratio of the silicon atoms in Si xC1-x grown at 500°C was tunable from 0.63 to 0.66 when reducing RF plasma power from 100 to 20 W. The low-plasma PECVD growth gave the SixC1-x an enhanced broadband absorption at 400.600 nm, where the highest optical absorption coefficient was 1.3-~105 cm.1. The silicon rich composition also reduced the optical bandgap energy from 2.05 to 1.49 eV. This type of red-shifted cutoff wavelength promoted solar energy conversion at the near-infrared region. Consequently, an ITO/p-Si xC1-x/n-SixC1-x/Al PVSC with a silicon molar ratio of 66% enhanced its conversion efficiency from 5 - 10.3 to 4.7% when the n-type SixC1-x thickness was reduced from 150 to 25 nm, which is attributed to the reduced series resistance to 0.6 ω and the increased shunt resistance to 1500 ω. © 2012 The Electrochemical Society.