Effect of ambient on the thermal parameters of a micromachined bolometer

The thermal characterization of bolometers is needed for optimal design as well as applications. In this letter, we present results of the effect of environment on the thermal properties of micromachined bolometers. We find that while in vacuum, the thermal response can be represented by a single time constant, in presence of an ambient gas, the thermal response can no longer be described by a single time constant. This will have a direct implication on frequency dependence of responsivity. We present a model to explain our data which involves the finite diffusion time in the ambient gas and the associated extra thermal mass.