Gallium-Doped Poly-Si:Ga/SiO2 Passivated Emitters to n-Cz Wafers With iV oc >730 mV

We form gallium-doped poly-Si:Ga/SiO
₂
passivated contacts on n-type Czochralski (n-Cz) wafers using ion implantation of Ga and Ga-containing spin-on dopants. After annealing and passivation with Al
₂
O
₃
, the contacts exhibit iVoc values of >730 mV with corresponding Joe values of <;5 fA/cm
²
. These are among the best-reported values for p-type poly-Si/SiO
₂
contacts. Secondary ion mass spectroscopic depth profile data show that, in contrast to B, Ga does not pileup at the SiO
₂
interface in agreement with its known high diffusivity in SiO
₂
. This lack of Ga pileup may imply fewer dopant-related defects in the SiO
₂
, compared with B dopants, and account for the excellent passivation.