Design of porous silicon /PECVD SiOx antireflection coatings for silicon solar cells

Abstract

The meso-poreux porous silicon layer (PS) has become an interesting material owing to its potential applications in many fields including optoelectronics and photovoltaics. PS layers were grown on the front surface emitter n+ of n+ -p mono-crystalline Si junction. The thickness of the PS formed and the porosity were measured by an ellipsometer as a function of time duration of anodization, and the variation law of the PS growth kinetics is established. Single layers PS antireflection coating (ARC) achieved around 9% effective reflectivity in the wavelength range between 400 and 1000nm on junction n+ -p solar cells. To reduce the reflectivity and improve the stability and passivation properties of PS ARC, the design of PECVD oxide silicon layers were investigated. SiOx layers of thickness of 105nm deposited on PS ARC showed a decrease of ~3.8% in the effective reflectivity, compared to the single layer PS ARC, improve the reflectivity of 55%. Voc measurements were carried out on all the samples by suns-Voc method and showed an improvement of the quality of the passivation brought by the oxide layer. Using the experimental reflectivity results and taking into account the passivation quality of the samples, the PC1D simulations predict an enhancement of the photogenerated current exceeding 49%.