Dresden 2006 – wissenschaftliches Programm
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DS: Dünne Schichten
DS 2: Optical properties of thin films II
DS 2.2: Vortrag
Montag, 27. März 2006, 12:00–12:15, GER 37
Optical properties of reactively sputtered chromium nitride films — •Kostas Sarakinos and Matthias Wuttig — I. Insitute of Physics (IA) RWTH Aachen University 52056 Aachen, Germany
A study of the optical properties of reactively sputtered CrxNy (1<x< 2, y<1) films is presented. The films have been sputtered in an Ar/N2 atmosphere at various values of the reactive gas (N2) flow from 0-50 sccm. Since the phase formation and the stoichiometry of the films upon the variation of the N2 flow has already been established [1], their effect on the optical properties is investigated. Spectroscopic Ellipsometry has been utilized for the optical characterization of the films. The ellipsometric spectra have been fitted using the combined Drude-Lorentz model. The unscreened Drude plasma energy has been used in order to monitor the evolution of the optical properties of the films. Films deposited at low N2 flows exhibit high values of and thus metallic conductivity. On the other hand, above 19 sccm of N2 flow , which is indicative for the absence of free electrons and electronic conductivity. The non metallic behavior above 19 sccm coincides with the predominance of a CrN1−x phase with rocksalt structure. Samples above 19 sccm N2 flow have been fitted with the Tauc-Lorentz model. Depending on the film stoichiometry within this regime a band gap up to 0.21 eV has been determined. This is in agreement with other experimental reports which state that the cubic CrN phase is a narrow band gap semiconductor.
[1] K. Sarakinos et al, submitted for publication