Hybrid functional method screens the p-type defects in wide gap semiconductorα-LiAlTe2

Abstract

Transparent conducting materials (TCMs) are vital in transparent electronics. Previous investigations show that ternary telluride α-LiAlTe2 possesses wide band gap of 3.13 eV, smaller hole-effective mass (0.69 m0) and high transmittance in visible light region [Phys. Scr. 99 (2024) 035923]. These characters imply that α-LiAlTe2 is a potential TCM. However, the research about its electrical conductivity is still lacking. In this work, we utilize hybrid functional method (Heyd-Scuseria-Ernzerhof (HSE06)) and screen the possible binary impurity phase. Under the thermodynamic equilibrium condition, the regions for the stable phase of α-LiAlTe2 are demarcated. The effects of the intrinsic defects and the possible p-type extrinsic defects are evaluated. We find the intrinsic defects Liint and Alint can induce the n-type conductivity. Substitution defects MgAl, CaAl, NTe, PTe and AsTe are p-type defects. Both MgAl and NTe are shallow acceptor defects with the transition energy level ε(0/-) of 0.24 eV and 0.21 eV above the valence band maximum (VBM). Under Te-rich and Li-relatively poor conditions, the acceptor defect NTe possesses the lower formation energies of 0.35 eV, implying that defect NTe could be fabricated by using the thermodynamic equilibrium fabrication method. At room temperature, the p-type electrical conductivity exceeds 60800 S/m when the hole density reaches 1020 cm-3. These results indicate that α-LiAlTe2 is a promising candidate for optoelectronic applications.