A method for alleviating the effect of pinhole defects from silicon nitride film in n-type rear-junction PERT silicon solar cells

Abstract

We investigated incorporation of a novel approach of phosphorous silicate glass layer thinning (PGT) process in the N-PERT process flow to minimise pinhole defects at the silicon nitride (Si3N4) surface. The thinning (PGT) process for optimum HF deposition time of 12 min resulted in excellent cell efficiency of ∼20.55% with pinhole free layer and high electrical yield (∼0% for I Rev > 1.5 A). After optimising technology, stability is also explored with and without PGT process line, which confirms advantages of this approach. This significant reverse failure reduction due to the proposed PGT process can eventually help in improving overall cell performance of the N-PERT devices. This process can be a part of strategy for reducing process cost of solar cell in any industrial mass production line with improved yield (reduction in reverse failure from 6.6 to 1.5% for one month of mass production). Thus, the PGT process with negligible electrical rejection and high yield increases the possibility of high throughput in mass production line.