Ordered Peierls distortion prevented at growth onset of GeTe ultra-thin films.
Using reflection high-energy electron diffraction (RHEED), the growth onset of molecular beam epitaxy (MBE) deposited germanium telluride (GeTe) film on Si(111)-(√3 × √3)R30°-Sb surfaces is investigated, and a larger than expected in-plane lattice spacing is observed during the deposition of the first two molecular layers. High-resolution transmission electron microscopy (HRTEM) confirms that the growth proceeds via closed layers, and that those are stable after growth. The comparison of the experimental Raman spectra with theoretical calculated ones allows assessing the shift of the phonon modes for a quasi-free-standing ultra-thin GeTe layer with larger in-plane lattice spacing. The manifestation of the latter phenomenon is ascribed to the influence of the interface and the confinement of GeTe within the limited volume of material available at growth onset, either preventing the occurrence of Peierls dimerization or their ordered arrangement to occur normally.
Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany.
Ruining
R
Wang
Department of Materials Science, University of Milano-Bicocca via R. Cozzi 55, 20125 Milano, Italy.
Davide
D
Campi
Department of Materials Science, University of Milano-Bicocca via R. Cozzi 55, 20125 Milano, Italy.
Marco
M
Bernasconi
Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Jamo
J
Momand
Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Bart J
BJ
Kooi
Eindhoven University of Technology, Department of Applied Physics, NL-5600 MB Eindhoven, The Netherlands.
Marcel A
MA
Verheijen
I. Physikalisches Institut, RWTH Aachen University, 52056 Aachen, Germany.|JARA-FIT and JARA-HPC, RWTH Aachen University, 52056 Aachen, Germany.
Matthias
M
Wuttig
Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany.
Raffaella
R
Calarco