Research about the method of measuring the ultra thin film and the plasma reaction under film growth using optical waveguides

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The thin film of about 10 nm of thickness was made to deposit on the multimode optical fiber sensor of the structure which exposed the core using CVD equipment, and with time progress, transmitted light intensity with a wavelength of 685-800 nm became small, and was saturated in about about 600 seconds.Moreover, in order to raise the sensitivity of a sensor, it is necessary to lengthen a sensor part or to make it thin. Then, the embedded type 3-dimensional waveguide with a 7micrometerx6micrometer core thinner than the former is used as a sensor and the optical physical-properties value of an a-Si : H film was measured. Consequently, the absorption spectrum with the same tendency as the case where a conventional optical fiber and conventional slab waveguide are used as a sensor was obtained. It carried out based on the absorption spectrum obtained here, and when asked for the optical energy band gap of the a-Si : H film made to deposit on a waveguide, the value about 1.70-1.72 [eV] was acquired irrespective of waveguide length. This is mostly in agreement with the value acquired by the conventional measuring method. Moreover, the measurement limit resulting from the amount of absorption becoming inadequate was a-Si : H thickness 50 [nm], when sensor length was set to 50 [mm] in the optical fiber of the diameter 110 im of a core. By the introduced measurement system, since it was a-Si : H thickness 3 [nm] when sensor length set to 50 [mm], improvement in large sensitivity is able to be aimed at. Since it is the 3-dimensional waveguide unlike slab waveguide, analysis by the finite element method with high accuracy is performed.