Progress in Surface Passivation of Heavily Doped n-Type and p-Type Silicon by Plasma-Deposited AlO $_{bm x}$ /SiN

We report an outstanding level of surface passivation for both n⁺ and p⁺ silicon by AlO_x/SiN_x dielectric stacks deposited in an inline plasma-enhanced chemical vapor deposition (PECVD) reactor for a wide range of sheet resistances. Extremely low emitter saturation current densities (J_0e) of 12 and 200 fA/cm² are obtained on 165 and 25 Ω/sq n⁺ emitters, respectively, and 8 and 45 fA/cm² on 170 and 30 Ω/sq p⁺ emitters, respectively. Using contactless corona-voltage measurements and device simulations, we demonstrate that the surface passivation mechanism on both n⁺ and p ⁺ silicon is primarily due to a relatively low interface defect density of <;10¹¹ eV^-1cm^-2 in combination with a moderate fixed negative charge density of (1-2) × 10¹² cm^-2. From advanced modeling, the fundamental surface recombination velocity parameter is shown to be in the order of 10⁴ cm/s for PECVD AlO_x/SiN_x passivated heavily doped n⁺ and p⁺ silicon surfaces.