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Title: Dielectric function in the NIR-VUV spectral range of (In{sub x}Ga{sub 1−x}){sub 2}O{sub 3} thin films

We determined the dielectric function of the alloy system (In{sub x}Ga{sub 1−x}){sub 2}O{sub 3} by spectroscopic ellipsometry in the wide spectral range from 0.5 eV to 8.5 eV and for In contents ranging from x = 0.02 to x = 0.61. The predicted optical transitions for binary, monoclinic β-Ga{sub 2}O{sub 3}, and cubic bcc-In{sub 2}O{sub 3} are well reflected by the change of the dielectric functions' lineshape as a function of the In content. In an intermediate composition range with phase-separated material (x ≈ 0.3…0.4), the lineshape differs considerably, which we assign to the presence of the high-pressure rhombohedral InGaO{sub 3}-II phase, which we also observe in Raman experiments in this range. By model analysis of the dielectric function, we derived spectra of the refractive index and the absorption coefficient and energy parameters of electronic band-band transitions. We discuss the sub-band gap absorption tail in relation to the influence of the In 4d orbitals on the valence bands. The data presented here provide a basis for a deeper understanding of the electronic properties of this technologically important material system and may be useful for device engineering.
Authors:
; ; ; ; ;  [1]
  1. Fakultät für Physik und Geowissenschaften, Institut für Experimentelle Physik II, Universität Leipzig, Linnéstr. 5, D-04103 Leipzig (Germany)
Publication Date:
OSTI Identifier:
22314538
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 5; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION; ALLOY SYSTEMS; BCC LATTICES; DIELECTRIC MATERIALS; ELLIPSOMETRY; EV RANGE 01-10; FAR ULTRAVIOLET RADIATION; FUNCTIONS; GALLIUM OXIDES; INDIUM OXIDES; MONOCLINIC LATTICES; REFRACTIVE INDEX; THIN FILMS; TRIGONAL LATTICES