Crystalline Silicon Cells Fabricated by Different Preclean Processes

Abstract

In this paper, we show that cell efficiency can be improved by simple preclean steps for silicon substrates. A very low reflectance of less than 1% is observed in the wavelength range from 450 to 700 nm for the silicon substrates precleaned using a NaOH solution followed by a gettering process. Lifetime measurements show that the silicon substrates treated by these preclean processes have a significantly improved minority carrier lifetime owing to a better surface condition than untreated silicon substrates. This result is further supported by the performance of the solar cells. A cell efficiency of 18.609% is achieved in the treated silicon substrates with a gain of 2.14% compared with the untreated silicon substrates.