Atomistic modeling of bond lengths in random and ordered III-V alloys

Abstract

This work provides comprehensive modeling for the bond length and angle distributions in random and spontaneously ordered ternary III-V alloys using empirical interaction potentials. The compounds InxGa1−xAs, GaAs1−xSbx, and InxGa1−xP were used as model systems due to their technological importance and the fact that ordered structures were observed experimentally in these materials. For random alloys, we reproduce the bimodal bond length distribution, which allows linear fits with slopes between 0.087 Å and 0.1059 Å for all bond types. The calculated values for dilute compositions slightly deviate from these functions, causing stronger deformations. In the case of CuPt-ordered structures, the bond length distribution is shown to collapse to four sharp peaks with an area ratio of 1:3:3:1, which originate from a different atom to atom distance within the different (111) planes and perpendicular to these. An essential consequence of this atomic arrangement is the different spacings for the different stacked binaries along the (111) direction, which also leads to strain values up to −0.819% for In0.5Ga0.5P and −1.827% for GaAs0.5Sb0.5. Furthermore, the broad bond angle distributions of random alloys collapse into two peaks for CuPt-like structures. On the other hand, CuAu-type ordering is shown to lead to a sharp bimodal bond length distribution but with five different groups of bond angles, which can be identified with the different atomic configurations in ternary zincblende crystals.

Thermal expansion of III–V materials in atomistic models using empirical Tersoff potentials

“…The structural properties of common elemental and III-V semiconductors, which crystallise in a diamond or zincblende lattice, can be modelled at an atomistic level using the Tersoff potential, where parameter sets are readily available [5][6][7][8]. These potentials were also proven to be reliable regarding the elastic behaviour or bond length distributions in binary compounds as well as random and spontaneously ordered ternary structures [9][10][11][12]. Such models were recently also extended to describe the behaviour of dopant atoms in III-V materials [13].…”

Atomistic modeling of interfaces in III–V semiconductor superlattices

“…Structural models using the Tersoff potential were also found to reproduce the experimentally observed bimodal bond length distribution random ternary alloys correctly [22,24]. Pronounced bond deformations were found in the case of CuPt-ordered alloys, resulting in built-in strain up to −1.8% in the case of soft alloys like GaAs 1−x Sb x .…”

Understanding semiconductor nanostructures via advanced electron microscopy and spectroscopy

“…Atomic ordering in ternary or quaternary semiconductors has been proven to have a dramatic effect on electronic band structure [ 109 , 110 , 111 ]. Several studies have theoretically and experimentally shown the difference of the physical properties between ordered and disordered structures such as InGaAs, GaAsSb, InGaP [ 112 ], AlInP [ 113 ] and AlGaInP [ 114 ] Previously, the use of scanning tunneling microscopy (STM) to identify atomic ordering has been reported [ 115 ]. Conventional HRTEM imaging associated with diffraction pattern methods also can provide information about the atomic ordering [ 116 , 117 , 118 , 119 , 120 ].…”

“…Atomic ordering in ternary or quaternary semiconductors has been proven to have a dramatic effect on electronic band structure [111][112][113]. Several studies have theoretically and experimentally shown the difference of the physical properties between ordered and disordered structures such as InGaAs, GaAsSb, InGaP [114], AlInP [115] and AlGaInP [116].…”