ATMOSPHERIC PRESSURE CHEMICAL VAPOR DEPOSITED ALUMINUM OXIDE/SILICON NITRIDE STACKS FOR PERC AND PERT SOLAR CELL CONCEPTS WITH HIGH PASSIVATION QUALITY

摘要

PERC (Passivated Emitter and Rear Cell) cells based on p-type crystalline Si and PERT (Passivated Emitter, Rear Totally diffused) cells based on n-type crystalline Si are getting more and more attractive in the commercial solar cell market. As a result of the highly competitive market, a low-cost production reached by high through-put and low upkeep is necessary. Atmospheric chemical vapor deposition (APCVD) tools fulfill these requirements and provide necessary high layer quality for high-efficiency solar cell production. Aluminum oxide (AlO_x) layers may in certain situations reach a surface passivation quality higher than atomic layer deposition (ALD) based AlO_x layers. In this contribution we demonstrate excess minority charge carrier lifetime values τ_(eff) up to 15 ms (surface recombination velocity S <0.3 cms-1) on n-type Czochralski-Si for undiffused samples as well as emitter saturation current density values j0e down to 21 fA/cm~2 on a 65 Ω/sq p~+ emitter for fired AlO_x/SiN_y:H stacks, common to PERC and PERT solar cell designs, respectively. We also determined the influence of reaction energy depending on heat delivery during APCV-deposition on the layer growth leading to a high temperature stable, low-pinhole density and blistering free layer (stack).