Does GaAs bulk lattice really expand due to defects in the low concentration regime?. (August 2020)

• Record Type: Journal Article
• Authors: Escaño, Mary Clare; Nguyen, Tien Quang
• Is Part Of: Solid state communications. Volume 316/317(2020)
• Publication Date: 2020-08
• Subjects: GaAs -- Lattice -- DFT -- Density of states -- Molecular dynamics; Solid state chemistry -- Periodicals; Solid state physics -- Periodicals; Chimie de l'état solide -- Périodiques; Physique de l'état solide -- Périodiques; 530.41
• DOI: 10.1016/j.ssc.2020.113918
• Languages: English
• ISSNs: 0038-1098

Abstract

Abstract: We conducted DFT calculations and molecular dynamics simulation to investigate the effect of small (less than 1%) concentrations of As-antisite (AsGa ) defect to the GaAs bulk lattice. We found that the lattice does not expand nor contract at 0.39% and 0.78% defect concentrations but retains the equilibrium lattice parameter of the GaAs. This clarifies the experimental observations of a plateau-type relationship of lattice expansion and defect concentration in the regime of very low AsGa content. We also found that the defect prefers clustered over dispersed structure. Using molecular dynamics simulations, we observed that such preservation of lattice parameter holds true even at 300 K. Also, interestingly, we found that the mid-gap state starts to appear at 0.78% defect concentration, while GaAs bulk with 0.39% AsGa mimics the semiconducting property of undefected GaAs. Highlights: No lattice expansion is observed in GaAs with low concentration of As-antisite defect. Defect structure is a cluster rather than isolated/dispersed. Mid-gap state appears at 0.78% AsGa concentration. GaAs with 0.39% As-antisite content mimics the semiconducting property of clean GaAs.