Micromachined Thermopile Arrays with Novel Thermo-electric Materials

Future missions to outer planets will have stringent limits on payload mass. Thermal imaging instruments to map planetary surfaces will be part of those payloads, and, consequently, will have to be compact and low mass. For thermal instruments, another key requirement will be state-of-the-art, highly sensitive detectors. Thermopiles are prime candidates for high-resolution thermal mapping in the far-infrared (17- to 250-μm wavelength) spectral range. Thermopile detector arrays can be made to be very lightweight and compact. Furthermore, they require very few ancillary components (e.g., readout electronics, optics, amplifiers), which can add to instrument volume and mass. The implementation of thermopiles on these missions is likely because they (1) generate an output voltage that is proportional to the incoming radiation within the spectral range being mapped; (2) do not require an electrical bias or an optical chopper; (3) have negligible 1/f noise; (4) are radiation hard; and (5) have a reported specific detectivity of 1 × 109 cm·Hz1/2/W at room temperature.