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<p>A systematic first-principles investigation of the structural, electronic, and optical properties of tellurium-doped zinc oxide ZnTeₓO<sub>1-x</sub> (<i>x</i> = 0, 1, 2, 3, 4, 5, and 100%) is presented. All calculations were carried out using the CASTEP plane-wave pseudopotential code under both the Local Density Approximation (LDA/CA-PZ) and the Generalized Gradient Approximation (GGA/PBE). Norm-conserving pseudopotentials were employed together with a plane-wave cutoff of 750&#xa0;eV, and Brillouin-zone sampling was performed on a 4 × 4 × 4 Monkhorst–Pack mesh. Te doping was modeled using the virtual crystal approximation (VCA), which allows low and fractional Te concentrations to be treated directly. Equilibrium geometries were obtained with the BFGS algorithm, and equation-of-state parameters were extracted by fitting total energy–volume data to the Murnaghan equation. Both functionals show that lattice constant and unit cell volume expand monotonically with Te content, from a₀ = 3.287&#xa0;Å (LDA) for pure ZnO to 4.304&#xa0;Å for ZnTe, while the bulk modulus falls from 220.6&#xa0;GPa to 42.6&#xa0;GPa (LDA), reflecting the progressive replacement of stiff Zn–O bonds by softer Zn–Te bonds. The electronic band gap decreases rapidly from 0.561&#xa0;eV (LDA) at <i>x</i> = 0 to zero at <i>x</i> ≥ 3%, suggesting a possible composition-driven semiconductor-to-metal transition within the LDA/GGA framework, driven by Te 5p–O 2p hybridization near the valence band maximum. This predicted gap closure should be interpreted with caution because standard LDA and GGA functionals underestimate band gaps<b>.</b> At full substitution (ZnTe), the gap re-opens at 1.498&#xa0;eV (LDA). Optical spectra, including absorption coefficient, reflectivity, refractive index, extinction coefficient, and complex dielectric function, computed within the independent-particle Kubo–Greenwood formalism, confirm a strong ultraviolet activity in ZnO and reveal a systematic red shift in the absorption edge and significant modification in the dielectric response upon Te incorporation. The enhanced visible-light absorption indicates that Te doping can improve the optical response of ZnO for potential photovoltaic, photocatalytic, and optoelectronic applications.</p>

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First-principles investigation of structural, electronic, and optical properties of Te-doped ZnO

  • 期刊论文

  • 发表日期：

    2026年7月13日

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  • F. Benlakhdar,
  • Idris Bouchama,
  • M. A. Ghebouli,
  • M. Fatmi,
  • S. Boudour,
  • Faisal K. Alanazi,
  • Mustafa Jaipallah Abdelmageed Abualreish,
  • Aseel Smerat,
  • Maha Alotaibi

摘要

A systematic first-principles investigation of the structural, electronic, and optical properties of tellurium-doped zinc oxide ZnTeₓO1-x (x = 0, 1, 2, 3, 4, 5, and 100%) is presented. All calculations were carried out using the CASTEP plane-wave pseudopotential code under both the Local Density Approximation (LDA/CA-PZ) and the Generalized Gradient Approximation (GGA/PBE). Norm-conserving pseudopotentials were employed together with a plane-wave cutoff of 750 eV, and Brillouin-zone sampling was performed on a 4 × 4 × 4 Monkhorst–Pack mesh. Te doping was modeled using the virtual crystal approximation (VCA), which allows low and fractional Te concentrations to be treated directly. Equilibrium geometries were obtained with the BFGS algorithm, and equation-of-state parameters were extracted by fitting total energy–volume data to the Murnaghan equation. Both functionals show that lattice constant and unit cell volume expand monotonically with Te content, from a₀ = 3.287 Å (LDA) for pure ZnO to 4.304 Å for ZnTe, while the bulk modulus falls from 220.6 GPa to 42.6 GPa (LDA), reflecting the progressive replacement of stiff Zn–O bonds by softer Zn–Te bonds. The electronic band gap decreases rapidly from 0.561 eV (LDA) at x = 0 to zero at x ≥ 3%, suggesting a possible composition-driven semiconductor-to-metal transition within the LDA/GGA framework, driven by Te 5p–O 2p hybridization near the valence band maximum. This predicted gap closure should be interpreted with caution because standard LDA and GGA functionals underestimate band gaps. At full substitution (ZnTe), the gap re-opens at 1.498 eV (LDA). Optical spectra, including absorption coefficient, reflectivity, refractive index, extinction coefficient, and complex dielectric function, computed within the independent-particle Kubo–Greenwood formalism, confirm a strong ultraviolet activity in ZnO and reveal a systematic red shift in the absorption edge and significant modification in the dielectric response upon Te incorporation. The enhanced visible-light absorption indicates that Te doping can improve the optical response of ZnO for potential photovoltaic, photocatalytic, and optoelectronic applications.