Passivation of Boron-Doped Industrial Silicon Emitters by Thermal Atomic Layer Deposited Titanium Oxide

Passivation of p⁺ -doped silicon is demonstrated by using water (H₂O)-based thermal atomic layer-deposited titanium oxide (TiO_x) films. Emitter saturation current density (J_{0 e}) values below 30 fA/cm² 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.