Three potential techniques for texturing commercial multicrystalline silicon solar cells are compared on the basis of reflectance measurements. Wet acidic texturing, which would be the least costly to implement, produces a modest improvement in reflection before antirflection coating and encapsulation, whereas maskless reactiveion etching texturing, and especially masked reactive-ion etched 'pyramids', generate a larger gain in absorption. After antireflection coating and encapsulation however, the differences between the methods are reduced. Short-circuit current measurements on wet acidic textured cells reveal that there is a significant additional current gain above that expected from the reduced reflection. This is attributed to both light-trapping and oblique coupling of incident light into the cell, resulting in generation closer to the junction.

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Reflection losses in passivated emitter solar cell polycrystalline silicon solar cells have been reduced by the application of a double layer antireflection coating of plasma enhanced chemical vapor deposition silicon nitride (PECVD SixNyHz). The layer was deposited in a single wafer parallel plate reactor powered by a 13.56 MHz rf power supply using SiH4 and NH3 as the reactive gases. The layers deposited had refractive indexes of 2.50 and 1.95 at HeNe wavelength and thicknesses of 42.5 and 64.5 nanometers (nm), respectively. The overall reflectance measured in the wavelength range between 350 and 1150 nm was 8.5%. The extinction coefficient of the high refractive index film showed a significant increase in absorption for short wavelengths. However, the improvement in current collection was higher than expected from the overall reflectance and absorption of the film. Short circuit current was increased by 49% and open circuit voltage increased by 3.3% when compared with uncoated cells. These results imply a passivation effect which increases the open circuit voltage beyond the value expected solely from the current collection addition.

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The possible benefits of phosphorus gettering as applied to production multicrystalline silicon wafers have been evaluated. After optimization of an open tube POCI, process, relatively low temperatures and short times have been found to significantly improve the minority carrier lifetime of most wafers. The possible gettering action stemming from the industrial process of phosphorus diffusion has also been investigated and found to be similarly effective. Average lifetimes of 45ps (diffusion length of 360pm) were obtained, with some wafers reaching maximum values up to 130ps. Lifetime monitoring of a commercial cell fabrication line has also enabled characterization of the voltage limits imposed by the standard emitter and aluminum back-surface-field. The results indicate that the bulk, as improved by emitter gettering, is generally not the limiting factor on cell performance.