Determination of linear bond Gruneisen parameter of GaAs using Extended X-ray Absorption Fine Structure (EXAFS)

The bond Gruneisen parameter of gallium arsenide's first shell was directly evaluated using temperature dependent Extended X-ray Absorption Fine Structure (EXAFS) data. A quasi-harmonic approach based on the anharmonic contribution to parallel Mean Square Relative Displacement (MSRD) has led to a positive and weakly temperature-dependent linear bond Gruneisen parameter (GP) of GaAs in the entire region (14-300 K). For all temperatures, we report linear bond GPs greater than those retrieved with EXAFS using an anharmonic Einstein model. The comparison with volumic Gruneisen parameters given by diffraction or dilatometric techniques shows a significant difference which could be attributed to the different definitions used to connect frequency and bond length (or lattice parameter). These results are an evidence of the inadequacy of the quasi-harmonic model to deal with local properties using EXAFS.

Automated summary

The study directly evaluated the bond Gruneisen parameter of gallium arsenide using temperature-dependent EXAFS data, revealing a positive and weakly temperature-dependent linear characteristic. However, the model showed inadequacy in dealing with local properties, displaying significant differences from parameters obtained using other techniques.