Chemical Interpretation of Charged Point Defects in Semiconductors: A Case Study of Mg ₂ Si

Abstract The electronic structures of charged point defects influence electrical and optical properties of semiconductors. Understanding the orbital interactions responsible for the electronic structures of defects therefore promotes a chemical intuition for defect‐driven mechanisms in semiconductors. In this tutorial, we discuss a molecular orbital theory‐based framework for understanding defect‐induced electronic states based on local chemical interactions between the defect and the atoms surrounding the defect site. By using Mg ₂ Si as a case study, we show how both the chemical interactions and molecular orbitals (i. e., wave functions) responsible for the charge state(s) of a defect can be understood from the bonding symmetry of the defect site. We anticipate that a chemistry‐based perspective of charged defects will enrich defect engineering efforts for electronic and optical materials.