Infrared emission from heated microcantilevers

An understanding of the thermal behavior of heated microcantilevers is essential to their use. In this article, we investigated the infrared (IR) emission of two silicon cantilevers with integrated solid-state heaters over the 2500-3000 cm^-1 spectral range. Two cantilevers were examined: the first had a heater surface area of 17 × 20 μm and the second had a heater surface area of 170 × 100 μm. We calculated the spectral power emitted by the cantilever based on the Planck function, dielectric function of the doped silicon at elevated temperatures, and cantilever spectral emissivity. Measurements of the cantilever spectral power compared well with predictions. The first cantilever had a radiative power of 4.2 μW at a heating power of 15.7 mW and maximum temperature of 1,150 K, and the second cantilever had a radiative power of 70.1 μW at a heating power of 54.9 mW and maximum temperature of 850 K. The cantilever emissive power depended on the spatial variation in the cantilever temperature and cantilever emissivity. It is also shown how the heated cantilever can be used as an IR source to acquire absorption spectra of polymer films in an IR spectrometer.