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

The bond Grüneisen 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 Grüneisen 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 Grüneisen 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. • GaAs' linear bond Grüneisen parameter (GP) is positive • GaAs' linear bond GP is weakly temperature dependent. • Linear bond GPs are higher than those given by anharmonic correlated Einstein model. • A marked difference is found between linear bond GPs given by EXAFS and XRD. • The quasi-harmonic model cannot deal with local properties using EXAFS. [ABSTRACT FROM AUTHOR]