Thermoreflectance dependence on Fermi surface electron number density perturbations
Click to view
(a) (solid lines) calculated with Eq. (4) as a function of temperature for two of the three different photonic excitations considered, along with for three different pump excitation energies (dashed lines). Note that the 1.55 eV excitation is not shown since the number of carriers excited from the -band to the conduction band from the 1.55 eV pulse is negligible, and reaches only 0.2% of at 3000 K. (b) Thermoreflectance response as a function of temperature. The difference in the thermoreflectance responses are more apparent at higher temperatures, and are attributed to the change in the conduction band number density induced by the pump-probe excitation. Also shown in this figure are thermoreflectance calculations assuming no conduction band number density perturbation but iterating until gives a best fit with the 3.10 (open circles) and 4.65 eV (open squares) thermoreflectance calculations. If a 3.10 eV pump excitation is absorbed (giving rise to due to population increase), and the increase in conduction band number density is not taken into account, the thermoreflectance spectra will incorrectly appear to reflect Au having an electron-phonon coupling factor of , a value that is nearly 25% too low. Similarly, for a 4.65 eV pump excitation, not accounting for the change in conduction band number density will result in an electron-phonon coupling factor that is 36% too low.
Article metrics loading...
Full text loading...