Source Of Infrared Radiation Based On Surface Plasmon Resonance Effect Of The New Mems Research

MEMS infrared gas sensor has excellent selectivity, sensitivity and stability owing to using spectral characteristics of gas as measurement. Thereinto, the research on MEMS infrared light source, which is the key components of it has been concerned in recent years. With the development of nanometer plasmonic crystals technology, it was noted that using the characteristics of two-dimensional metallic subwavelength (hole diameter less than half of the wavelength of incident light) round hole arrays to select a specific wavelength of light and enhance extraordinary optical transmission (EOT), it is possible to provide an effective means of fabricating MEMS infrared radiation light source having a very good selection and enhancement in a specific range of infrared light.The work of the thesis included five facts shown below:1. The relationship of the<100> Si bulk etching characteristic with the temperature and concentration of KOH/IPA mixed solution. It is found that, with higher concentration of IPA and lower temperature, the cutting ratio will be smaller. With IPA 100% concentration, at 30℃, the best cutting ration 1.05 is found.2. A novel SPR-MEMS infrared light source have been designed and fabricated based on the research on infrared radiation characteristics of the SPR device. Four different light source structure have been designed, the infrared light sources are structured by Si—SiO2(650nm)—Si3N4(200nm)—Pt(200nm) then patterned with a periodic array of perforations (hole depth=8μm, the hole shape is circular). The SiO2 and Si3N4-are insulation layers, the Pt is filament material. It is found that the peak wavelength was proportional to the lattice constant. For emitters with same lattice constant, the larger the ratio, the stronger the reflection. For emitters with same ratio, the smaller the diameter, the stronger the reflection. The emitters with hexagonal array among three different symmetries of hole array, has the best reflection spectrum. The characteristic testing of the source is completed with thermograph and spectrograph. All sources fabricated produce a wide rang of IR emitting over the 2-14um wavelength region, where many gases have their infrared absorption. The temperature of the membrane could reach more than 850℃, when the electronic current is about 28mA. Radiation peak is found on the spectrum, but not at the calculated wavelength, because of the thick rudimental Si substrate.3. The relationship between the transmission spectrum of the emitter and the thickness of SU-8 layer of metal/dielectric/metal(M/D/M) structure in mid-infrared waveband(2-14 micron) has been studied. The emitter is structured by Au/SU-8/Au, which the thickness of Au layer is 20nm, and the SU-8 layer is between 0.2 to 1.2 micron. The transmission spectrum has been tested out with Varian 4100 FT-IR. The experimental data has been compared and analyzed with simulation results from finite-difference time-domain(FDTD) calculation. It is found out that the structure with SU-8 layer thinner than 1 micron has much larger transmission peak strength than the ones with thicker SU-8 layer, with the largest transmission peak strength found when the thickness of SU-8 layer is 360nm., and the red-shift of the wavelength of the transmission peak is also observed.