First principles calculations of Al AsxP1-x ternary nanocrystal alloying composition

Mohammed T. Hussein

doi:10.30723/ijp.v15i33.140

Abstract

III-V zinc-blende AlP, AlAs semiconductors and their alloy Aluminum Arsenide phosphide Al AsxP1-x ternary nanocrystals have been investigated using Ab- initio density functional theory (Ab-initio-DFT) at the generalized-gradient approximation (GGA) level with STO-3G basis set coupled with large unit cell method (LUC). The dimension of crystal is found around (1.56 – 2.24) nm at a function of increasing the sizes (8, 16, 54, 64) with different concentration of arsenide (x=0, 0.25, 0.5, 0.75 and 1) respectively. Gaussian 03 code program has been used throughout this study to calculate some of the physical properties such as the electronic properties energy gap, lattice constant, valence and conduction band as well as density of state. Results show that the lattice constant increases with the increasing in the arsenide concentration in the alloy. The total energy, cohesive energy, electron affinity and ionization potential as well as ionicity for these concentrations have been reported.

Highlights

Aluminum arsenide (AlAs) is one of the most important electronic and optoelectronic materials because of its frequent incorporation into GaAsbased heterostructures [1, 2]
The two semiconductors AlAs and AlP form a continuous series of alloys denoted by Al As1-x Px, where x is the mole fraction of AlAs in the alloy, AlAs/AlP super lattices are attractive due to their potential applications in optoelectronic devices because they are expected to become direct band gap materials [3]
The obtained results appear to be reasonable as well as the number of atoms increases beside to that the number of mutual interactions resulting in an increase in total energy

Summary

Introduction

Aluminum arsenide (AlAs) is one of the most important electronic and optoelectronic materials because of its frequent incorporation into GaAsbased heterostructures [1, 2]. AlAs is a subject of extensive theoretical studies ranging from the semiempirical to the first principles methods [4], within the density functional theory framework using both pseudo potential [5], and all electron approaches. Investigated the structural and electronic properties of AlAs and AlP compounds using the full potential linearized augmented plane wave plus local orbitals method based on density functional theory. In the most common formulation of quantum mechanics, solving this problem means solving the N-electron Schrödinger equation: This equation involving the Hamiltonian operator Ĥ, Ψ the wave function, and the Eigen value E. Several theories gave approximate solutions to calculate the electronic structure properties for Al AsxP1xnanocrystal for core atoms 8, 16, 54 and 64, one of these powerful theories is the density functional theory (DFT). Is well established [15] but the best choice for f (n , n , n , n ) is still a matter of debate

Results and discussion

Number of core atoms per LUC

Number of core atoms LUC

Nnmber of core atoms per LUC

Conclusions