Micromachined Mid-Infrared Emitter for Fast Transient Temperature Operation for Optical Gas Sensing Systems

A micromachined thermal emitter for fast transient temperature operation with a novel hot-plate concept is presented. This concept is based on a nonaxis-symmetric design with excellent mechanical properties during temperature modulation combined with high thermal decoupling. Especially, the mechanical stress induced by the thermal expansion of the hot-plate and their suspension was improved. This results in a reduced sensitivity for buckling of the hot-plate. The thermal emitter is fabricated using silicon on insulator (SOI) technology and KOH-etching. Different suspension structures were realized and mechanical and thermal characterizations were performed. Besides the realization of the new hot-plate suspension design, a high thermal emission at wavelengths > 5 ¿m has been achieved using ceramic coatings for emissivity enhancement. This kind of emission tuning owns-in contrast to the typical surface and bulk structuring methods-the possibility to act simultaneously as a heater passivation.