First-Principles Study on Structural Mechanical Anisotropic Electronic and Thermal Properties of III-Phosphides: XP (X = Al Ga or In) in the P6422 Phase

摘要

The structural, mechanical, electronic, and thermal properties, as well as the stability and elastic anisotropy, of P ( = Al, Ga, or In) in the 6 22 phase were studied via density functional theory (DFT) in this work. 6 22- P ( = Al, Ga, or In) are dynamically and thermodynamically stable via phonon spectra and enthalpy. At 0 GPa, 6 22- P ( = Al, Ga, or In) are more rigid than - P ( = Al, Ga, or In), of which 6 22- P ( = Al or Ga) are brittle and 6 22-InP is ductile. In the same plane (except for (001)-plane), 6 22-AlP and 6 22-InP exhibit the smallest and the largest anisotropy, respectively, and 6 22- P ( = Al, Ga, or In) is isotropic in the (001)-plane. In addition, Al, Ga, In, and P bonds bring different electrical properties: 6 22-InP exhibits a direct band gap (0.42 eV) with potential application for an infrared detector, whereas 6 22- P ( = Al or Ga) exhibit indirect band gap (1.55 eV and 0.86 eV). At high temperature (approaching the melting point), the theoretical minimum thermal conductivities of 6 22- P ( = Al, Ga, or In) are AlP (1.338 W∙m ∙K ) > GaP (1.058 W∙m ∙K ) > InP (0.669 W∙m ∙K ), and are larger than those of - P ( = Al, Ga, or In). Thus, 6 22- P ( = Al, Ga, or In) have high potential application at high temperature.