Effect of Au contamination on the electrical characteristics of a “model” small-angle grain boundary in n-type direct silicon bonded wafer

Abstract

We have investigated the electrical characteristics of a “model” small-angle grain boundary (GB) in n-type direct silicon bonded wafers with intentional Au contamination. It is found that the Au aggregated at the GB can cause new acceptorlike states, developing a potential barrier. The density of Au-related GB states is about 1–2×1012 cm−2 eV−1 in the energy range of Ec-0.65–Ec-0.33 eV. With the energy level becoming deeper, the corresponding electron capture cross-section becomes larger, in the order of magnitude 10−16–10−15 cm2. It is believed that Au contamination has strong influence on the electrical properties of GB. These results are interesting for the GB engineering of n-type multicrystalline silicon solar cells for terrestrial application.