Dissolution of electrically inactive phosphorus by low temperature annealing
In this study we investigate the dissolution of electrically inactive phosphorus complexes by low temperature annealing after the POCl3 diffusion process. This has the immediate consequence that the existing near-surface emitter volume SRH recombination can be reduced. Thereby, a significant reduction of emitter saturation current density j0E is achieved without driving the emitter further into the silicon substrate. For short-term temperature treatments well below the POCl3 diffusion temperature, a reduction of up to -60 fA/cm2 has been achieved. This study increases our understanding of the formation and dissolution of electrically inactive phosphorus complexes during post-annealing processes.
Improvement of industrial phosphorus diffused emitters and impact on solar cell efficiencies
In this study, we investigate the importance of the minority carrier lifetime (τp0) and surface recombination velocity (SRV) of industrial n-type emitters in improving emitter performance and improving solar cell efficiency. When emitters with higher τp0 values are applied to Al-BSF and PERC solar cells separately, they show slightly different responses to the increase in τp0. Simulation results indicate that PERC solar cells receive a larger efficiency enhancement with the same increase in τp0 than that for Al-BSF cells. This is due to the fact that emitter recombination can be a major contributor to efficiency loss for solar cell structures like PERC where the rear surface is well passivated by dielectric stacks. Additionally, LDSE cells have a stronger dependence on the surface passivation quality, especially for the PERC structure.
Characterization of ceramic composite membrane filters for hot gas cleaning
Abstract Novel composite ceramic membrane filters suitable for hot gas cleaning operations have been prepared from fly ash and titania particles on stainless steel woven mesh substrates. Both membranes had a structure like a solid packed bed with a thickness of less than 100 μm. In the domain of laminar flow, significant differences in the pressure drop between experimental results and those predicted from the Kozeny-Carman relationship were found, particularly for flow through the titania membrane. Membrane filters with extremely small pores such as the titania membrane are greatly affected by slip up to 80% in permeability at elevated temperatures. Efficiencies of filtration of typical coal fired power station exhaust fly ashes were found to be greater than 909% for both titania and ash membranes, whilst there was greater variation in the pressure drops in the ash membrane than in the titania at typical gas flows.