Estimation of Interfacial Fixed Charge at Al 2 O 3 /SiO 2 Using Slant-Etched Wafer for Solar Cell Application

Al 2 O 3 with a negative fixed charge prepared by atomic layer deposition has been reported to improve surface passivation properties for Si-solar cell applications. The high negative fixed charge at the SiO 2 /Al 2 O 3 interface facilitates a low surface recombination velocity and a high effective lifetime, which result in greater performance. In this study, we adopted an effective method using a slant-etched sample with various thicknesses of SiO 2 to estimate the charge densities of both the bulk and interface of Al 2 O 3 deposited by atomic layer deposition. We found a direct correlation between lifetime and total charge density in Al 2 O 3 , which are strong functions of film thickness and annealing condition.