TY  - JOUR
AU  - Kerres, Peter
AU  - Zhou, Yiming
AU  - Vaishnav, Hetal
AU  - Raghuwanshi, Mohit
AU  - Wang, Jiangjing
AU  - Häser, Maria
AU  - Pohlmann, Marc
AU  - Cheng, Yudong
AU  - Schön, Carl-Friedrich
AU  - Jansen, Thomas
AU  - Bellin, Christophe
AU  - Bürgler, Daniel E.
AU  - Jalil, Abdur Rehman
AU  - Ringkamp, Christoph
AU  - Kowalczyk, Hugo
AU  - Schneider, Claus M.
AU  - Shukla, Abhay
AU  - Wuttig, Matthias
TI  - Scaling and Confinement in Ultrathin Chalcogenide Films as Exemplified by GeTe
JO  - Small
VL  - 18
IS  - 21
SN  - 1613-6810
CY  - Weinheim
PB  - Wiley-VCH
M1  - FZJ-2022-02239
SP  - 2201753 -
PY  - 2022
AB  - Chalcogenides such as GeTe, PbTe, Sb2Te3, and Bi2Se3 are characterized by an unconventional combination of properties enabling a plethora of applications ranging from thermo-electrics to phase change materials, topological insulators, and photonic switches. Chalcogenides possess pronounced optical absorption, relatively low effective masses, reasonably high electron mobilities, soft bonds, large bond polarizabilities, and low thermal conductivities. These remarkable characteristics are linked to an unconventional bonding mechanism characterized by a competition between electron delocalization and electron localization. Confinement, that is, the reduction of the sample dimension as realized in thin films should alter this competition and modify chemical bonds and the resulting properties. Here, pronounced changes of optical and vibrational properties are demonstrated for crystalline films of GeTe, while amorphous films of GeTe show no similar thickness dependence. For crystalline films, this thickness dependence persists up to remarkably large thicknesses above 15 nm. X-ray diffraction and accompanying simulations employing density functional theory relate these changes to thickness dependent structural (Peierls) distortions, due to an increased electron localization between adjacent atoms upon reducing the film thickness. A thickness dependence and hence potential to modify film properties for all chalcogenide films with a similar bonding mechanism is expected.
LB  - PUB:(DE-HGF)16
C6  - 35491494
UR  - <Go to ISI:>//WOS:000789168100001
DO  - DOI:10.1002/smll.202201753
UR  - https://juser.fz-juelich.de/record/907840
ER  -