A spectroscopic ellispometric study of the tunability of the optical constants and thickness of GeO{sub x} films with swift heavy ions

Journal Article · Thu Sep 15 00:00:00 EDT 2011 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3638700· OSTI ID:22038704

Vijayarangamuthu, K; Singh, Chaman; Rath, Shyama ^[1]; Kabiraj, D ^[2]

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1. Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)
2. Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)

Sub-stoichiometric GeO{sub x} films were fabricated by electron-beam evaporation method. The films were irradiated with 100 MeV Ag{sup 7+} ions at fluences between 1 x 10{sup 12} and 1 x 10{sup 14} ions-cm{sup -2}. Spectroscopic ellipsometric measurements were performed in air at room temperature. The values of the layer thickness and refractive index were extracted from ellipsometry using a multilayer analysis and the Tauc Lorentz model. The refractive index (at 633 nm) of the as-deposited GeO{sub x} film was estimated to be 1.860 and decreased to 1.823 for films irradiated at an ion fluence of 1 x 10{sup 14} ions-cm{sup -2}. The thickness of the films also decreased after irradiation and is due to a sputtering induced by the ion beam. The change in the refractive index with ion fluence is attributed to a stoichiometric change and structural transformation represented by GeO{sub x}{yields} Ge + GeO{sub y} (y > x) occurring due to a thermal spike induced by ion irradiation. Swift heavy ions thus provide a scope for modulating the refractive index of GeO{sub x} films. The thickness and stoichiometric changes are supported by Rutherford backscattering measurements.

• OSTI ID: 22038704
• Journal Information: Journal of Applied Physics, Vol. 110, Issue 6; Other Information: (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ELECTRON BEAMS
ELLIPSOMETRY
EVAPORATION
FOURIER TRANSFORMATION
GERMANIUM
GERMANIUM OXIDES
INFRARED SPECTRA
ION BEAMS
IRRADIATION
LAYERS
RADIATION EFFECTS
REFRACTIVE INDEX
RUTHERFORD BACKSCATTERING SPECTROSCOPY
SOLIDS
STOICHIOMETRY
TEMPERATURE RANGE 0273-0400 K
THERMAL SPIKES
THIN FILMS
VACUUM COATING