Local structure of In0.5Ga0.5As from joint high-resolution and differential pair distribution function analysis

Abstract

High resolution total and indium differential atomic pair distribution functions (PDFs) for In0.5Ga0.5As alloys have been obtained by high energy and anomalous x-ray diffraction experiments, respectively. The first peak in the total PDF is resolved as a doublet due to the presence of two distinct bond lengths, In-As and Ga-As. The In differential PDF, which involves only atomic pairs containing In, yields chemical specific information and helps ease the structure data interpretation. Both PDFs have been fit with structure models and the way in that the underlying cubic zinc-blende lattice of In0.5Ga0.5As semiconductor alloy distorts locally to accommodate the distinct In-As and Ga-As bond lengths present has been quantified.

Analysis of occupational and displacive disorder using the atomic pair distribution function: a systematic investigation

“…For a simple binary compound consisting of atoms A and B, the corresponding partials would contain only AA, BB or AB (same as BA) atoms. More details can be found in a recent study of the total and differential PDF of In 1−x Ga x As by Petkov et al (1999). The program DISCUS used here can also be used to calculate or refine any partial PDF of a given structure.…”

High real-space resolution structure of materials by high-energy x-ray diffraction

“…Extra positional disorder, manifested by enlarged temperature factors, has been found on both metal and As sites as well. Both the static displacement and the positional disorder have been found to peak at a composition x = 0.5 [6,7].…”

“…More experimental details can be found in refs. [6,7]. Experimental reduced structure factors and the corresponding atomic PDFs G(r) are shown in Figs.…”

High-resolution atomic distribution functions of disordered materials by high-energy X-ray diffraction

“…The sample was placed inside a rectangular cavity resonating in the TE102 mode at 71.2 GHz [4]. Our system enables the cavity to be rotated with…”

“…1. To quantify the distortions in the alloy, simple models based on the 8-atom unit cell of the zinc-blende lattice were fit to the experimental PDFs [4]. The PDF for GaAs is fit well with a model based on the perfect zinc-blende structure as can be seen in Fig.…”