Dresden 2020 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 104: Ultrafast Electron Dynamics III (joint session O/MA)

O 104.8: Vortrag

Donnerstag, 19. März 2020, 12:15–12:30, WIL B321

Investigation of coherent phonons at the interface of GaP/Si(001) heterostructures — •Steven Youngkin1, Gerson Mette1, Kunie Ishioka2, Wolfgang Stolz1, and Ulrich Höfer11Fachbereich Physik, Philipps Universität Marburg, Germany — 2National Institute for Material Science, Tsukuba, Japan

Breaking of the bulk lattice atomic ordering by a surface leads to a plethora of novel and interesting physical phenomena such as new vibronic states, commonly known as surface phonon modes. However, very little is known about the vibronic states that arise at an interface of two solids.

Here, we use coherent phonon spectroscopy to study the interface vibronic system of GaP/Si(001) heterostructures, which represent a structurally well characterized model system of a polar/non-polar inorganic semiconductor interface. By measuring the transient reflectivity change of the probe beam at various pump photon energies, we can monitor the energy dependence of the coherent excitation of phonon modes with a resolution limited by the ultrashort laser pulses. Our studies reveal the existence of a low-frequency phonon mode with a frequency of 2 THz. This vibrational mode is absent in both bulk systems and is therefore assigned to originate from the buried interface between GaP and Si.

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