Low Temperature Back-Surface-Field (BSF) Technology for Crystalline Silicon (c-Si) Thin Film Solar Cells Based on Heterojunctions between Boron-Doped P-Type Hydrogenated Amorphous Silicon and c-Si
We propose a low temperature back-surface field (BSF) technology for crystalline silicon (c-Si) thin film solar cells. The BSF structure has a heterojunction between a p-type c-Si substrate and a boron (B)-doped p-type hydrogenated amorphous silicon (a-Si:H) layer deposited on the back surface of the c-Si substrate at 200degC. The back-surface recombination velocity, Sb, of minority carriers can be reduced to less than 1000 cm/s in this structure, while the value of S b is 106 cm/s when a B-doped p-type layer is epitaxially grown on the c-Si substrate. We have clarified, from internal photoemission (IPE) and attenuated-total-reflection Fourier transform infrared (ATR-FTIR) spectroscopy measurements, that possible reasons for the observed low value of Sb are (1) the band lineup of the heterojunction (HJ) between B-doped p-type a-Si:H and c-Si and (2) the hydrogen passivation of defects in B-doped a-Si:H
Processed optimization for excellent interface passivation quality of amorphous/crystalline silicon solar cells
Abstract This study evaluates the interface passivation quality of the amorphous/crystalline heterointerface and the performance of the heterojunction with intrinsic thin layer solar cells via values of a plasma parameter characterized by the deposition pressure ( p )×electrode distance ( d ). Increasing the product of p × d leads to a lower crystalline fraction and higher hydrogen content, and enhances the c-Si surface passivation. This p × d evaluation factor is also compared with other evaluation factors, such as the silane depletion fraction and film-crystallinity. The tendencies of minority carrier lifetimes with respect to these evaluation factors were similar. Using the highest p × d value of 48, the photovoltaic parameter of the device yielded an open-circuit voltage of up to 710 mV, in turned giving an efficiency of 19.12%.
Numerical Simulation of Induction Heating Process of Continuous Casting Slab
Compared with traditional blazing furnace, the Continuous Casting-Direct Rolling is an advanced manufacturing steel technology, which can reduce energy waste, decrease pollution and enhance efficiency. The characteristics of steels during induction heating are complex, the change of material properties with temperature makes exact analysis methods very difficult to implement. Therefore, a powerful computer aided numerical tool (i.e., finite difference analysis) is selected to numerically model the induction heating process in this paper. The mathematic model coupling with electromagnetic field and thermal field was established, and it was solved by finite difference method (FDM), thus the slab temperature distribution and its variation with time were obtained, and the characteristics in whole induction heating process were studied. To validate the program feasible, the results were evaluated and compared with experiment results, which showed that the simulation results are reliable and effective. The skin effect in heating process from the two results was studied and demonstrated, the temperature change caused by different parameters such as the induced power intensity and the corner radian were also presented, which indicate that the slab temperature can be heated uniformly through adjusting these parameters, thus the continuous casting slab can meet the rolling requirement.