Correlation between Optical Properties and Chemical Composition of Sputter-Deposited Germanium Oxide (GEOX) Films (Postprint)
Interim rept. 6 May 2010-17 Feb 2014
AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH FUNCTIONAL MATERIALS DIV
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Germanium oxide GeOx films were grown on 100 Si substrates by reactive Direct-Current DC magnetron sputter-deposition using an elemental Ge target. The effects of oxygen gas fraction, U O2 Ar O2, on the deposition rate, structure, chemical composition and optical properties of GeOx films have been investigated. The chemistry of the films exhibits an evolution from pure Ge to mixed Ge GeO GeO2 and then finally to GeO2 upon increasing U from 0.00 to 1.00. Grazing incidence X-ray analysis indicates that the GeOx films grown were amorphous. The optical properties probed by spectroscopic ellipsometry indicate that the effect of U is significant on the optical constants of the GeOx films. The measured index of refraction n at a wavelength k of 550 nm is 4.67 for films grown without any oxygen, indicating behavior characteristic of semiconducting Ge. The transition from germanium to mixed Ge GeO GeO2 composition is associated with a characteristic decrease in n k 550 nm to 2.62 and occurs at 0.25. Finally n drops to 1.60 for U 0.50 1.00, where the films become GeO2. A detailed correlation between n, k and stoichiometry in DC sputtered GeOx films is presented and discussed.
- Inorganic Chemistry