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Effects of Biaxial Strains and High Pressure on the Structural, Electronic, and Vibrational Properties of DC‐HgM2Te4 (M = Al, In)

First‐principles calculations are performed to study the effects of biaxial strains and high pressure on the structural, electronic, and lattice dynamical properties of defect chalcopyrite HgM2Te4 (M = Al, In) semiconductors. The evolutions of optimized structural parameters, band‐gap energy, crystal‐field splitting energy, and ‐point phonon frequencies with the biaxial strain and pressure have been analyzed. The optimized lattice parameters are reasonable compared with the existing experimental results. Both compounds undergo an indirect to direct band gap transition under tensile , however, the semiconductors retain their indirect band gap character under pressure. The increasing pressure pushes the crystal‐field‐splitting hole (CH) band downwards; in contrast, the increasing biaxial strain makes the CH band shift upwards, which results in that the crystal‐field splitting energies decrease from positive to negative. The pressure‐induced softness of low‐frequency modes around the X point suggests that both compounds become dynamically instable. Atomic displacement patterns show that the high frequency modes are mainly determined by the vibrations of group‐III cations.

Biaxial strains and high pressure have a crucial effect on tailoring the physical properties of defect chalcopyrites such as DC‐HgAl2Te4 and DC‐HgIn2Te4. Different external forces play different roles in adjusting the Eg values of the defect chalcopyrites in this work. Regulating the tensile biaxial strain can make an indirect‐to‐direct band gap transition.

Autoren:   Shaobo Zhang, Liwei Shi, Chuanfu Huang, Wangsuo Xia, Lanyang Zhang, Haiyan Zhu
Journal:   physica status solidi (b)
Jahrgang:   2018
Seiten:   n/a
DOI:   10.1002/pssb.201700574
Erscheinungsdatum:   15.01.2018
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