A spectroscopic ellispometric study of the tunability of the optical constants and thickness of GeOx films with swift heavy ions

作者：Vijayarangamuthu K; Singh Chaman; Kabiraj D; Rath Shyama^*

来源：Journal of Applied Physics, 2011, 110(6): 063512.

DOI：10.1063/1.3638700

Sub-stoichiometric GeOx films were fabricated by electron-beam evaporation method. The films were irradiated with 100 MeV Ag7+ ions at fluences between 1 x 10(12) and 1 x 10(14) ions-cm(-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 GeOx film was estimated to be 1.860 and decreased to 1.823 for films irradiated at an ion fluence of 1 x 10(14) ions-cm(-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 GeOx > Ge vertical bar GeOy (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 GeOx films. The thickness and stoichiometric changes are supported by Rutherford backscattering measurements.

• 出版日期2011-9-15