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Abstract: The Hydrogenated silicon nitride (SiN x :H) using plasma enhanced chemical vapor deposition is widely used in photovoltaic industry as an antireflection coating and passivation layer. In the high temperature firing process, the SiN x :H film should not change the properties for its use as high quality surface layer in crystalline silicon solar cells. For optimizing surface layer in crystalline silicon solar cells, by varying gas mixture ratios (SiH4 + NH3 + N2, SiH4 + NH3, SiH4 + N2), the hydrogenated silicon nitride films were analyzed for its antireflection and surface passivation (electrical and chemical) properties. The film deposited with the gas mixture of SiH4 + NH3 + N2 showed the best properties in before and after firing process conditions. The single crystalline silicon solar cells fabricated according to optimized gas mixture condition (SiH4 + NH3 + N2) on large area substrate of size 156 mm × 156 mm (Pseudo square) was found to have the conversion efficiency as high as 17.2%. The reason for the high efficiency using SiH4 + NH3 + N2 is because of the good optical transmittance and passivation properties. Optimized hydrogenated silicon nitride surface layer and high efficiency crystalline silicon solar cells fabrication sequence has also been explained in this study. [Copyright &y& Elsevier]

Abstract: The relationship between aluminum fire-through and the properties of a-SiNx:H thin films was investigated to aid their use as dielectric layers in rear side and front passivation layers in crystalline solar cells. Aluminum fire-through was shown to depend on the refractive index and the deposition rate of the films. Refractive index, density and deposition rate increased with increasing SiH4/NH3 ratio, while the etching rate decreased. Aluminum fire-through occurred in a sample of refractive index 2.0 during fast deposition but not when the deposition rate was slow. Aluminum fire-through occurred during extended firing, despite it not occurring during normal firing by RTP. The results of this work demonstrate that refractive index was the major determinant of aluminum fire-through, and that the aluminum and the a-SiNx:H thin film reacted immediately at the beginning of firing at a rate determined by the deposition rate. [Copyright &y& Elsevier]

Abstract: We grew Cu2S nanowires vertically on Cu foil by gas–solid reaction with a gas mixture of O2 and H2S. The electrical contact properties between the Cu2S nanowires and Cu foil were investigated using a modified current–voltage–temperature plot. The Cu/Cu2S layer exhibited the characteristics of a Schottky barrier with a barrier height of ∼0.72eV, which was closer to the value for Cu/Cu2O than to Cu/Cu2S. Energy dispersive spectroscopy results showed the presence of Cu-oxide between the Cu2S nanowires and Cu foil. The overall structure was Cu/Cu-oxide/Cu2S and the electrical properties were controlled by the Cu/Cu-oxide. [Copyright &y& Elsevier]

Abstract: Using pulsed, plasma-enhanced chemical vapor deposition system, silicon nitride films were deposited from SiH4 and NH3 at room temperature. Duty ratio was controlled in a range of 20–100% incrementally by 20% at radio frequency bias powers of 50, 70, and 90 W. Reflectance was studied as a function of the process parameters mentioned earlier. The impact of duty ratio on the reflectance was prominent at 70 W and this was strongly correlated with a ratio of high ion energy to low ion energy. Interestingly, the reflectance at other powers yielded a strong correlation with high ion energy flux. A comparison study with other film properties revealed that the reflectance decreased with a decrease in film thickness. A neural network model was constructed to predict various effects of diagnostic variables on the reflectance. [Copyright &y& Elsevier]