Acoustic phonons in InSb probed by time‐resolved X‐ray diffraction

Abstract

AbstractAcoustical phonons in InSb were induced with femtosecond light pulses and probed by diffraction of ultrashort X‐ray pulses in the crystal lattice. The time dependent transient X‐ray diffraction signal due to elastic lattice deformation was measured with subpicosecond resolution. The elastic lattice deformation depends on the temporal evolution of the energy transfer from excited electrons in the semiconductor into the lattice. As already shown in previous investigation a conventional thermoelastic model is not sufficient to describe this coupling process. Here a complex simulation including a two temperature model of the electron and lattice as well as the microscopic behavior of the electron plasma is applied to explain important effects like thermal carrier diffusion and band gap deformation found in the lattice deformation experiments. When this model is used, with realistic values for both pump laser fluences and bulk material constants, excellent agreement between the experimentally observed time dependent lattice deformation and calculated values is obtained throughout the observation period. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)