Cooled Silicon-On-Insulator Diode Thermometer: Toward THz Passive Imaging

Terahertz passive imaging requires high sensitivity detectors, with Minimum Detectable Power (MDP) under the picowatt range. An antenna-coupled cooled microbolometer, incorporating a lateral PiN-like diode as thermometer, could represent a solution. In a first step, such diode performances have to be investigated, especially the temperature coefficient of current (TCC) and the low frequency noise. Prototypes were fabricated on Silicon-On-Insulator (SOI) 4” wafers with 50-nm active silicon layer. I-V and noise measurements down to 81K were useful to derive the electrical MDP of the future bolometer, already reaching 6.6 pW at 10 frames per second.