Fabrication of Carbon-Nanotube-Based Bolometers

A bolometer is a device that measures the energy of incident electromagnetic radiation by converting the photon energy into heat on an isolated absorber. The heat will be measured by the resistance change of the absorber which is a function of the energy gained from incident photons and the energy lost to the heat sinks of the system. Since carbon nanotube (CNT) forests have been shown to be nearly perfect optical absorption material in wavelengths ranging from 200 nm to 200 μm, a CNT coated absorber will convert virtually all incident photons into heat. The CNT bolometers will be fabricated from silicon-on-insulator wafers. The absorber will be a CNT-coated island suspended by bridges connected to heat sinks and will have the necessary circuitry for thermistor calibration and temperature measurement. The lengths of these bridges affect the characteristics of the sensor. Longer bridges have better heat retention which results in higher sensitivity, while shorter bridges lose heat quickly and allow for the improved detection of quickly-changing light sources. The dimensions of the construction also affect the prevalence of thermal and flicker noise. There will be 40 designs with varying dimensions of the absorbers and suspended supports in one 4 wafer. Details of the fabrication process and challenges will be presented