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Title: Experimental evidence of zone-center optical phonon softening by accumulating holes in thin Ge

We discuss the impact of free carriers on the zone-center optical phonon frequency in germanium (Ge). By taking advantage of the Ge-on-insulator structure, we measured the Raman spectroscopy by applying back-gate bias. Phonon softening by accumulating holes in Ge film was clearly observed. This fact strongly suggests that the phonon softening in heavily-doped Ge is mainly attributed to the free carrier effect rather than the dopant atom counterpart. Furthermore, we propose that the free carrier effect on phonon softening is simply understandable from the viewpoint of covalent bonding modification by free carriers.
Authors:
; ; ;  [1]
  1. Department of Materials Engineering, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656 (Japan)
Publication Date:
OSTI Identifier:
22492401
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 6; Journal Issue: 1; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ATOMS; CHARGE CARRIERS; COVALENCE; DIELECTRIC MATERIALS; DOPED MATERIALS; FILMS; GERMANIUM; HOLES; MODIFICATIONS; PHONONS; RAMAN SPECTROSCOPY; ZONES