Development of wide band gap p-a-SiOxCy:H using additional trimethylboron as carbon source gas

Abstract

We report p-type a-SiOxCy:H thin films which were fabricated by introducing additional Trimethylboron (TMB, B(CH3)3) doping gas into conventional standard p-type a-SiOx:H films. The TMB addition into the condition of p-a-SiOx:H improved optical bandgap from 2.14 to 2.20 eV without deterioration of electrical conductivity, which is promising for p-type window layer of thin film solar cells. The suggested p-a-SiOxCy:H films were applied in amorphous silicon solar cells and we found an increase of quantum efficiency at short wavelength regions due to wide bandgap of the new p-layer, and thus efficiency improvement from 10.4 to 10.7% was demonstrated in a-Si:H solar cell by employing the p-a-SiOxCy:H film. In case of a-SiOx:H cell, high open circuit voltage of 1.01 V was confirmed by using the suggested the p-a-SiOxCy:H film as a window layer. This new p-layer can be highly promising as a wide bandgap window layer to improve the performance of thin film silicon solar cells.