A hybrid functional method for screening the p-type defects in wide gap semiconductor α-LiAlTe2

Abstract

Transparent conducting materials (TCMs) are vital in transparent electronics. Previous investigations show that ternary telluride α-LiAlTe₂ possesses a wide band gap of 3.13 eV, a smaller hole-effective mass (0.69m₀) and high transmittance in the visible light region [S. Kang et al., Phys. Scr., 2024, 99, 035923]. These characteristic features imply that α-LiAlTe₂ is a potential TCM. However, the research on its electrical conductivity is still lacking. In this work, we utilize a hybrid functional method (Heyd–Scuseria–Ernzerhof (HSE06)) to screen the possible binary impurity phase. Under the thermodynamic equilibrium conditions, 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 that the intrinsic defects Li_int and Al_int can induce n-type conductivity. Substitution defects Mg_Al, Ca_Al, N_Te, P_Te and As_Te are p-type defects. Both Mg_Al and N_Te are shallow acceptor defects with the transition energy levels ε(0/−) at 0.24 eV and 0.21 eV above the valence band maximum (VBM). Under Te-rich and Li-relatively poor conditions, the acceptor defect N_Te possesses a lower formation energy of 0.35 eV, implying that defect N_Te could be fabricated by using the thermodynamic equilibrium fabrication method. At room temperature, the p-type electrical conductivity exceeds 60 800 S m⁻¹ when the hole density reaches 10²⁰ cm⁻³. These results indicate that α-LiAlTe₂ is a promising candidate for optoelectronic applications.