PROGRESS WITH INDUSTRIALLY FEASIBLE EXCELLENT SURFACE PASSIVATION OF HEAVILYDOPED p-TYPE AND n-TYPE CRYSTALLINE SILICON BY PECVD SiOx/SiNx WITH OPTIMISED ANTIREFLECTIVE PERFORMANCE

摘要

In this work we show progress in surface passivation of both n+ and p+ silicon using an industrial costeffectivelow-temperature PECVD (plasma-enhanced chemical vapour deposition) SiOx/SiNx dielectric stack. Very lowemitter saturation current densities J0e of < 10 fA/cm2 and < 15 fA/cm2, respectively, were obtained for n+ and p+diffusions (sheet resistance of ~150 sq) passivated by these SiOx/SiNx stacks after a standard industrial firing pr°Cess.These stacks feature a very low fixed charge density (+ 1011 elementary charges/cm2) and excellent interface quality(Dit,midgap of ~3×1010 eV-1cm-2) after an industrial firing step as measured by contactless corona-voltage (C-V)measurements. Based on the contactless C-V measurements, we also explain the mechanism of surface passivation tobe dominated by chemical passivation rather than field-effect passivation. Implied V°C values of > 700 mV (no metal)were measured on the PECVD SiOx/SiNx passivated n+np+ structures after industrial firing. With excellent optical andpassivation properties, these films are suitable for cost-effective high-efficiency industrial n-type and p-type siliconwafer solar cells. It is important to note that this complete stack was deposited in a standard industrial PECVD reactorusing a SiH4/NH3 gas mix for the SiNx films and a SiH4/N2O gas mix for the SiOx films.