Passivation property of Al2O3 thin film for the application of n-type crystalline Si solar cells

The passivation property of Al2O3 thin film formed using atomic layer deposition (ALD) for the application of crystalline Si solar cells was investigated using microwave photoconductance decay (mu-PCD). After post-annealing at 400 degrees C for 5 min, Al2O3 thin film exhibited the structural stability having amorphous nature without the interfacial reaction between Al O-2(3) and Si. The post-annealing at 400 degrees C for 5 min led to an increase in the relative effective lifetime of Al2O3 thin film. This could be associated with the field effective passivation combined with surface passivation of textured Si. The capacitance-voltage (C-V) characteristics of the metal-oxide-semiconductor (MOS) with Al2O3 thin film post-annealed at 400 degrees C for 5 min was carried out to evaluate the negative fixed charge of Al2O3 thin film. From the relationship between flatband voltage (V FB) and equivalent oxide thickness (EOT), which were extracted from C-V characteristics, the negative fixed charge of Al2O3 thin film was calculated to be 2.5 x 10(12) cm(-2), of which value was applicable to the passivation layer of n-type crystalline Si solar cells.