Estimation of Interfacial Fixed Charge at Al2O3/SiO2 Using Slant-Etched Wafer for Solar Cell Application

Abstract

Al2O3 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 SiO2/Al2O3 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 SiO2 to estimate the charge densities of both the bulk and interface of Al2O3 deposited by atomic layer deposition. We found a direct correlation between lifetime and total charge density in Al2O3, which are strong functions of film thickness and annealing condition. (C) 2011 The Japan Society of Applied Physics