Electronic structure of intrinsic defects in c-gallium nitride: Density functional theory study without the jellium approximation

Journal Article · Fri Jun 10 00:00:00 EDT 2022 · Physical Review. B

DOI:https://doi.org/10.1103/physrevb.105.235110· OSTI ID:1877120

Edwards, Arthur H.  ^[1]; Schultz, Peter A.  ^[2]; Dobzynski, Richard M. ^[3]

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1. Air Force Research Lab. (AFRL), Kirtland Air Force Base, NM (United States)
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
3. RMD Materials Science, LLC, Currituck, NC (United States)

Here, we report the first nonjellium, systematic, density functional theory (DFT) study of intrinsic and extrinsic defects and defect levels in zinc-blende (cubic) gallium nitride. We use the local moment counter charge (LMCC) method, the standard Perdew-Becke-Ernzerhoff (PBE) exchange-correlation potential, and two pseudopotentials, where the Ga 3$$\textit{d}$$ orbitals are either in the core ($d^0$) or explicitly in the valence set ($$d^{10}$$). We studied 64, 216, 512, and 1000 atom supercells, and demonstrated convergence to the infinite limit, crucial for delineating deep from shallow states near band edges, and for demonstrating the elimination of finite cell-size errors. Contrary to common claims, we find that exact exchange is not required to obtain defect levels across the experimental band gap. As was true in silicon, silicon carbide, and gallium arsenide, the extremal LMCC defect levels of the aggregate of defects yield an effective LMCC defect band gap that is within 10% of the experimental gap (3.3 eV) for both pseudopotentials. We demonstrate that the gallium vacancy is more complicated than previously reported. There is dramatic metastability–a nearest-neighbor nitrogen atom shifts into the gallium site, forming an antisite, nitrogen vacancy pair, which is more stable than the simple vacancy for positive charge states. Our assessment of the $d^0$ and $$d^{10}$$ pseudopotentials yields minimal differences in defect structures and defect levels. The better agreement of the $d^0$ lattice constant with experiment suggests that the more computationally economical $d^0$ pseudopotentials are sufficient to achieve the fidelity possible within the physical accuracy of DFT, and thereby enable calculations in larger supercells necessary to demonstrate convergence with respect to finite size supercell errors.

• Research Organization: Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States). Center for Integrated Nanotechnologies (CINT)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); US Air Force Office of Scientific Research (AFOSR); USDOE Laboratory Directed Research and Development (LDRD) Program
• Grant/Contract Number: NA0003525; FA9550-17RVCOR505
• OSTI ID: 1877120
• Report Number(s): SAND2022-8144J; 707418; TRN: US2307372
• Journal Information: Physical Review. B, Vol. 105, Issue 23; ISSN 2469-9950
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY