Defects can play an important role in the optoelectronic function of semiconducting materials. Thus, an accurate and detailed knowledge of the influence of defects is central to the design of new high-performance materials. We present a first-principles many-body perturbation theory approach to the study of point defects in bulk and monolayer semiconductors. Using a GW/BSE description of the optical and electronic proeprties, we develop an approach to systematically identify defects, and their associated trap state energies. For a +1 charged nitrogen vacancy within bulk GaN, analysis of the bandstructure and optical absorption spectrum indicates that this particular defect does not significantly alter the energetics of the material. However, analysis of the electron-hole correlation function reveals that the low-energy excitations are comprised of a mixed bulk-like and defect-like character. Additionally, we investigate the influence of selected charged defects on the optoelectronic properties of two-dimensional GeSe, for which we predict defects introduce deep mid-gap trap states. We determine that the optoelectronic properties are significantly influenced by the presence of these defects.

Many-body perturbation theory analysis of point defects in bulk and monolayer semiconducting materials

256th National Meeting (2018)

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