Evaluation of Temperature and Germanium Concentration Dependence of EXAFS Oscillations in Si-Rich Silicon Germanium Thin Films

Abstract

We measured the influence of the germanium (Ge) nearest neighbor atom on the lattice vibration of silicon germanium (SiGe) thin films on silicon substrate, which is expected as a material for next-generation electronic and thermoelectric devices, by x-ray absorption fine structure measurement. The amount of changes in the Debye-Waller factor (Δσ 2) of each sample were estimated from the obtained extended x-ray absorption fine structure spectra, and it was experimentally clarified that the lattice vibration of the SiGe films were different from that of Ge. On the other hand, it is considered that the lattice vibration of the SiGe films were suppressed by the compressive strain, since Δσ 2 have hardly changed with the Ge concentration. The Einstein temperature estimated from Δσ 2 decreased with increasing Ge concentration, suggesting that the thermal conductivity of SiGe film can be controlled by Ge concentration.