Ab initioEPR parameters for dangling-bond defect complexes in silicon: Effect of Jahn-Teller distortion

Abstract

A dangling bond (db) is an important point defect in silicon. It is realized in crystalline silicon by defect complexes of the monovacancy $V$ with impurities. In this work, we present spin-polarized density-functional theory calculations of EPR parameters ($g$ and hyperfine tensors) within the GIPAW formalism for two kinds of db defect complexes. The first class characterizes chemically saturated db systems, where three of the four dangling bonds of the isolated vacancy are saturated by hydrogen ($V{H}_{3}$) or hydrogen and oxygen (hydrogen-oxygen complex, $VOH$). The second kind of db consists of systems with a Jahn-Teller distortion, where the vacancy includes either a substitutional phosphorus atom (the $E$ center, $VP$) or a single hydrogen atom ($VH$). For all systems we obtain excellent agreement with available experimental data, and we are therefore able to quantify the effect of the Jahn-Teller distortion on the EPR parameters. Furthermore we study the influence of strain to obtain further insights into the structural and electronic characteristics of the considered defects.