Excellent passivation of boron emitters is realised using AlOx/SiNx dielectric stacks deposited in an industrial inline plasma‐enhanced chemical vapour deposition reactor. Very low emitter saturation current density (J0e) values of 10 and 45 fA/cm2 are obtained for 180 and 30 Ω/sq planar p+ emitters, respectively. For textured p+ emitters, the J0e was found to be 1.5–2 times higher compared with planar emitters. The required thermal activation of the AlOx films is performed in a standard industrial fast‐firing furnace, making the developed passivation stack industrially viable. We also show that an AlOx thickness of 5 nm in the AlOx/SiNx stack is sufficient for obtaining a J0e of 18 fA/cm2 for planar 80 Ω/sq p+ emitters, which corresponds to a 1‐sun open‐circuit voltage limit of the solar cell of 736 mV at 25 °C. Copyright © 2012 John Wiley & Sons, Ltd.

Passivation of p + -doped silicon is demonstrated by using water (H 2 O)-based thermal atomic layer-deposited titanium oxide (TiO x ) films. Emitter saturation current density (J 0 e ) values below 30 fA/cm 2 are obtained on textured p + -doped samples with a sheet resistance in the 80-120 Ω/sq range. This low emitter saturation current density would allow open-circuit voltages up to 720 mV when this TiO x film is used in n-type silicon wafer solar cells with a front boron emitter. In addition, the optical properties of TiO x make it an excellent option for use as antireflection coating on the silicon wafer solar cell after encapsulation. Thus, the results demonstrated in this paper could enable interesting new routes for future high-efficiency n-type silicon wafer solar cells.

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Multidimensional numerical simulation of boron diffusion is of great relevance for the improvement of industrial n-type crystalline silicon wafer solar cells. However, surface passivation of boron diffused area is typically studied in one dimension on planar lifetime samples. This approach neglects the effects of the solar cell pyramidal texture on the boron doping process and resulting doping profile. In this work, we present a theoretical study using a two-dimensional surface morphology for pyramidally textured samples. The boron diffusivity and segregation coefficient between oxide and silicon in simulation are determined by reproducing measured one-dimensional boron depth profiles prepared using different boron diffusion recipes on planar samples. The established parameters are subsequently used to simulate the boron diffusion process on textured samples. The simulated junction depth is found to agree quantitatively well with electron beam induced current measurements. Finally, chemical passivation on planar and textured samples is compared in device simulation. Particularly, a two-dimensional approach is adopted for textured samples to evaluate chemical passivation. The intrinsic emitter saturation current density, which is only related to Auger and radiative recombination, is also simulated for both planar and textured samples. The differences between planar and textured samples are discussed.