Study on surface passivation by YZO/AlOx stacking double layer for crystalline Si solar cells

We investigated stacking double layer structure, the Y
₂
O
₃
-ZrO
₂
composite film (YZO) on AlO
_x
, for the field effect passivation with high negative fixed charge densities on p-type Si. The composition spread YZO films were deposited at room temperature by using combinatorial sputtering technique. The fixed charge densities were extracted from the flat band voltage shift in the capacitance-voltage characteristics. The as-deposited ZrO
₂
film incorporated with 15% Y
₂
O
₃
stacking on the ALD AlO
_x
structure showed the highest negative fixed charge of -1.9 × 10
¹²
cm
^-2
. The field effect passivation can be controlled by the negative fixed charges in the YZO film depending on the composition and dipole uniformly formed at AlO
_x
/Si interface. After annealing in the oxygen atmosphere, passivation properties deteriorated caused by the Al diffusion at the YZO/AlO
_x
interface.