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

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/cm
²
are obtained on 165 and 25 Ω/sq n
⁺
emitters, respectively, and 8 and 45 fA/cm
²
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 <;10
¹¹
eV
^-1
cm
^-2
in combination with a moderate fixed negative charge density of (1-2) × 10
¹²
cm
^-2
. From advanced modeling, the fundamental surface recombination velocity parameter is shown to be in the order of 10
⁴
cm/s for PECVD AlO
_x
/SiN
_x
passivated heavily doped n
⁺
and p
⁺
silicon surfaces.