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First-principles study of intrinsic point defects in MgSiAs2
1Key Laboratory of Strongly-Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China. bcpan@ustc.edu.cn.
Physical Chemistry Chemical Physics : PCCP
|February 20, 2019
Summary
MgSiAs2 shows promise for infrared-nonlinear optical applications. Native point defects, particularly cation antisites, limit its transparency and doping capabilities, though growth conditions have a modest impact.
Area of Science:
- Materials Science
- Solid State Physics
- Optoelectronics
Background:
- Magnesium silicon arsenide (MgSiAs2) is a promising material for infrared-nonlinear optical (IR-NLO) applications.
- Its potential is linked to excellent second harmonic generation (SHG) performance and a high laser damage threshold (LDT).
Purpose of the Study:
- To systematically investigate native point defects in MgSiAs2.
- To understand the influence of these defects on the material's optical and electronic properties.
Main Methods:
- First-principles calculations utilizing the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional.
- Evaluation of defect formation energies and transition levels at the dilute limit.
Main Results:
- Thirteen different point defects were studied, with nine exhibiting deep transition levels that may limit the transparency spectrum.
- Cation antisites (MgSi and SiMg) were identified as the most abundant defects at equilibrium, acting as acceptors and donors respectively.
- Low formation energies of these antisites lead to Fermi level pinning and constrain carrier doping.
Conclusions:
- Native point defects significantly influence the optical and electronic properties of MgSiAs2.
- The identified defects, particularly cation antisites, pose challenges for achieving optimal IR-NLO performance.
- Growth conditions have a limited effect on defect formation energies and carrier concentrations, suggesting intrinsic material limitations.
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