First-Principles Study of Bi-Doping Effects in Hg_0.75Cd_0.25Te

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Materials Science

Background:

• Mercury cadmium telluride (HgCdTe) is a crucial semiconductor alloy for infrared optoelectronic applications.
• Understanding impurity behavior is vital for tailoring HgCdTe properties.
• Bismuth (Bi) is investigated as a potential dopant in HgCdTe.

Purpose of the Study:

• To investigate the structural and electronic properties of Bi-doped Hg_0.75Cd_0.25Te.
• To elucidate the amphoteric substitution behavior of Bi in this alloy.
• To analyze the influence of Bi impurities on the electronic band structure.

Main Methods:

• First-principles calculations using density functional theory (DFT).
• Employing the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional for accurate band gap correction.
• Analysis of structural relaxations, charge densities, electron localization functions (ELFs), density of states (DOSs), and band structures.

Main Results:

• Bismuth (Bi) exhibits amphoteric behavior in Hg_0.75Cd_0.25Te, consistent with Group V elements.
• Detailed analysis of charge densities and ELFs clarifies bonding characteristics between Bi and host atoms.
• Calculated DOSs, band structures, and defect band charge densities reveal the impact of Bi on the electronic properties.

Conclusions:

• Bi acts as a typical amphoteric dopant in Hg_0.75Cd_0.25Te.
• The study provides insights into the fundamental behavior of Bi impurities in narrow-gap semiconductors.
• This research contributes to the understanding of defect physics in HgCdTe for advanced material design.