Abstract
Bi2O2Se is an emerging semiconducting, air-stable layered material (Nat. Nanotechnol. 2017, 12, 530; Nano Lett. 2017, 17, 3021), potentially exceeding MoS2 and phosphorene in electron mobility and rivalling typical Van der Waals stacked layered materials in the next-generation high-speed and low-power electronics. Holding the promise of functional versatility, it is arousing rapidly growing interest from various disciplines, including optoelectronics, thermoelectronics and piezoelectronics. In this work, we comprehensively study the electrical properties of the native point defects in Bi2O2Se, as an essential step toward understanding the fundamentals of this material. The defect landscapes dependent on both Fermi energy and the chemical potentials of atomic constituents are investigated. Along with the bulk defect analysis, a complementary inspection of the surface properties, within the simple context of charge neutrality level model, elucidates the observed n-type characteristics of Bi2O2Se based FETs. This work provides important guide to engineer the defects of Bi2O2Se for desired properties, which is key to the successful application of this emerging layered material27.
Highlights
Bi2O2Se is an emerging semiconducting, air-stable layered material
Indirect band gap of 0.76 eV with conduction band minimum (CBM) near Γ point is in good agreement with the value of 0.80 eV measured by angle-resolved photoemission spectroscopy[15]
Defect landscape is found to vary with Fermi energy and the chemical potentials of the atomic constituents
Summary
Our calculations are based on density functional theory within the generalized gradient approximation,[20] using the Cambridge Sequential Total Energy Package21. 90 atoms’ Bi2O2Se supercell is used as the host of various native point defects, where the lattice constants are fixed to the calculated values. For BiSe, a ξ(1+/0) transition level occurs at 0.30 eV above the VBM (charge states from 1− to 5+ are considered), indicating that it is a deep donor center It is the third most stable defect next to Sev and Ov in p-Bi2O2Se under the (Se-poor, Bi-rich) condition, compensating the p-type conductivity. For BiO, transition levels ξ(4+/2+) and ξ(2+/0) occur at 0.33 eV and 0.50 eV above the VBM, respectively (charge states from 1− to 5+ are considered) It is a deep donor center and it compensates the p-type. Sein assumes positively charged state as long as the Fermi level is below the transition level ξ(1+/0) at 0.26 eV above the VBM, acting as an acceptor compensating center in p-type Bi2O2Se. On average, each Se atom in the triselenide anion acquires intermediate oxidation state between −2 and 0. PDOSs of Oin° (Sein0) (Fig. 7c,d) show that the seleninyl ion SeO−2 (triselenide anion Se3−4) has filled antibonding frontier orbital states below (a)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
