Naoki Kishi

Lifetime evaluation of self-modulated MEMS infrared light source made of single crystalline silicon

We have developed a self-modulated light source for infrared spectroscopy. The filaments of the light source that are made of single crystalline silicon can be realized by Micro-Electro-Mechanical Systems (MEMS) technology. The experimental prototypes have been fabricated and the characteristics of the devices have been measured. The lifetime of the light source has been evaluated by the resistance drift of the filaments. The operating condition at which the drift is less than 1.0%/year has been estimated and demonstrated.

Antenna-coupled rectifying diode for IR detection

An antenna-coupled rectifying SChottky Barrier DIode (SBD) for IR detection is fabricated on Si by IC processes. Aluminum thin film antenna of 30 micrometers length and 1.5 micrometers width is formed on thermally grown SiO2 layer on Si. At the end of antenna, rectifying SBD of 0.03 micrometers diameter is formed by focused ion beam (FIB) milling technique. Ion current monitoring system with FIB largely reduced the size of milled hole, which is conventionally limited by ion beam waist diameter. IR radiation from CO2 laser of 10.6 micrometers in wavelength and 0.55 W in power is used for device evaluations. Signal dependence on incident angle of CO2 laser radiation and dependence on diode bias voltage are evaluated. We confirmed the rectifying operation of antenna- coupled SBD at IR region and experimentally obtained rectified voltage of 173 nV. The NEP is calculated to be 1.94 X 10-6 W/Hz-1/2.

CO/sub 2//H/sub 2/O gas sensor with a MEMS Fabry-Perot filter

An electrostatically driven tunable MEMS Fabry-Perot filter with wide wavelength range from 2.5 /spl mu/m to 4.5 /spl mu/m has been developed for nondispersive infrared (NDIR) CO/sub 2//H/sub 2/O gas sensors. The Fabry-Perot filter is equipped with the NDIR system, and the principle of this gas sensing method has been confirmed.

Miniature CO 2 Gas Sensor (1 cm 3 ) using Silicon Microbolometers and Micro Variable Infrared Filter

A miniature CO2 gas sensor of 1 cm3 volume has been developed. Its operating principle is based on non-dispersive infrared (NDIR) dual-beam dual-wavelength measurement. This gas sensor consists of a conventional miniature lamp as an infrared source, a gas cell and an infrared detecting module, that is assembled from two single-crystal silicon microbolometers, a wide bandpass filter and a micro variable infrared filter (MVIF) in a TO-5 package. The resolution (σ) of the CO2 concentration is 20 ppm at 2000 ppm for the time constant and the roll-off rate of the output low-pass filter of 3 sec and 12 dB/octave, respectively.