Birefringent waveguides in thermally oxidized nitrogen-doped sputtered tantalum films
| Autor: | R.J. Boynton, W.D. Westwood, B.K. Maclaurin, S. J. Ingrey, F.C. Livermore |
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| Rok vydání: | 1976 |
| Předmět: |
Thermal oxidation
Materials science Anodizing Doping Metals and Alloys Analytical chemistry Tantalum chemistry.chemical_element Surfaces and Interfaces Nitrogen Surfaces Coatings and Films Electronic Optical and Magnetic Materials Amorphous solid chemistry Sputtering Electrical resistivity and conductivity Materials Chemistry |
| Zdroj: | Thin Solid Films. 35:1-9 |
| ISSN: | 0040-6090 |
| Popis: | Nitrogen-doped tantalum films were deposited by d.c. sputtering in a semicontinuous d.c. diode system. Their electrical properties varied with nitrogen in a similar manner to that generally reported; e.g. the resistivity first decreased from 200 μω cm to a minimum value of 140 μω cm and then increased monotonically. The film density also decreased with increasing nitrogen flow. The films were oxidized both by anodization and by the thermal oxidation in an oxygen atmosphere at 550°C. For a given anodization voltage, the capacitance decreased by approximately 50% when the nitrogen content in the sputtered film reached an estimated 30 at.%. The thermal oxides acted as waveguides for He-Ne light and their refractive indices were strongly dependent on nitrogen concentration. For Ta 2 O 5 , the indices for TE and TM modes were 2.21 but both decreased by different amounts as the nitrogen concentration increased. For the highest nitrogen concentration, the values for the TE and TM modes were 1.91 and 1.82 respectively. The birefringence must be due to local asymmetry around the Ta atom which is caused by the presence of nitrogen but the mechanism responsible for the ordering in amorphous or randomly oriented micropolycrystalline films is not clear. |
| Databáze: | OpenAIRE |
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