17.1% efficient truncated-pyramid inversion-layer silicon solar cells

Metal-insulator-semiconductor inversion-layer (MIS-IL) silicon solar cells can be fabricated in a simple and cost-effective way. In order to exceed the present performance level, the front surface recombination losses have to be reduced for improved open-circuit voltages. With the novel truncated-pyramid concept it is possible to perform the passivation of the front surface prior to the MIS-contact formation. Thus, the restriction to temperatures around 250°C for the front surface passivation is eliminated and the effective recombination velocity S_eff of the inversion-layer emitter can be strongly reduced to 200-400 cm/s. Point-like contact areas are opened at the tips of the random pyramids by means of chemical-mechanical polishing. As a result, V_OC increases by about 40 mV and the efficiency improves to 17.1%