Structural, electronic, optical and mechanical properties of InP alloyed with Zn, Si, Sn and S under pressure: First-principles calculation

Abstract

Structural, electronic, optical and mechanical properties of Zn, Si, Sn and S substitutions on InP supercell under pressure in zinc blende (ZB) and rock salt (RS) phases are presented using first-principles method. Cohesive energy and enthalpy difference are observed, and found that the order of possible spontaneous process in experimental growth, which introduced from enthalpy difference, is (In,Zn)P > In(P,S) > In(Si,P) > In(Sn,P). The lower enthalpy difference in RS structure indicates that the spontaneous process of impurity substitution can be occurred in RS more than in ZB. Phase transition from ZB to RS reduces the strain on crystal lattice by the increasing of chemical bond length. The chemical bonding of Zn-P in ZB is the strongest sharing electrons when compared with other compounds, Zn-P>Si-In>S-In>Sn-In. The dielectric performance of InP is reduced by the alloying effect, and it transforms to the conductor performance as high frequencies. Order of photo-absorption coefficient in range of visible light with the impurities is Sn>Si>S>Zn, and it reduces under high-pressure. Mechanical stability of InP alloys was observed, and satisfied the Born stability criteria. The impurities reduce Shear modulus of pure InP. Poisson's ratio of InP alloys in RS exhibit small deformation and high isotropy, corresponding to high-symmetry cubic phase. B/G ratio indicates that ductility of InP alloys is reduced, when it transformed to RS. The ductility of InP is induced by the alloying effect due to the B/G ratio increasing.