Abstract
The results of a full potential linear muffin-tin orbital (FP-LMTO) study on the electronic properties of cubic zinc blende type group III-V semiconductors AlP and AlAs under pressure are presented. The equilibrium lattice constant, bulk modulus, pressure derivative of bulk modulus and the phase transition pressure at which the compounds undergo structural phase transition from ZnS to NaCl and NaCl to CsCl are predicted from the total energy calculations. The ground state properties and band gap values are compared with the experimental results. At normal pressure AlP and AlAs are indirect bandgap semiconductors. When the pressure is increased there is enhanced overlapping between the wave functions of the neighbouring atoms. As a result the widths of the valence and empty conduction bands increase. These changes lead to the narrowing and indirect closing of band gaps in AlP and AlAs (metallization). On further increase of pressure, AlP and AlAs become superconductors, and these materials come under the class of electron-phonon-mediated high pressure superconductors. The superconducting transition temperatures (Tc) of AlP and AlAs are obtained as a function of pressure for CsCl structure. It is also confirmed that the metallization, structural phase transition and onset of superconductivity do not occur simultaneously in these compounds.
Highlights
The enormous properties like ductility, light weight and high strength of aluminum compounds makes it the best choice for many areas of constructive as well as other important engineering applications [1]
Even though we have obtained the band structure for V/Vo values from 1.0 to 0.3, we have presented here the band structures of AlP and AlAs along the symmetry directions Γ-X-W-L-Γ-K and the corresponding density of states of AlP and AlAs (Figs.1 to 8).The volume compressions corresponding to V/Vo=1.0 and V/Vo=0.52 for
The ground state properties and structural phase transitions of AlP and AlAs are studied from their total energies obtained from our calculation
Summary
The enormous properties like ductility, light weight and high strength of aluminum compounds makes it the best choice for many areas of constructive as well as other important engineering applications [1]. Group III-V semiconductors AlP and AlAs have been extensively studied because they are considered important technological materials in electronic and opto electronic applications[3,4,5,6]. The effect of pressure on the electronic properties of group III-V compounds can be investigated experimentally in many ways[7,8]. The technological applications of all the above compounds require significant progress in the fundamental understanding of their behaviour at normal and high pressures. Aluminum compounds (AlP and AlAs) crystallize in zinc blende (ZnS) structure. Aluminum compounds (AlP and AlAs) crystallize in zinc blende (ZnS) structure. [9,10]
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