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

We investigated stacking double layer structure, the Y₂O₃-ZrO₂ 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 ZrO₂ film incorporated with 15% Y₂O₃ stacking on the ALD AlO_x structure showed the highest negative fixed charge of -1.9 × 10¹² 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.