Dynamical theory of a high-temperature superconductor photo-thermoelectrical bolometer

In this paper, we develop a dynamic theory starting from the basic heat bal ance equation for a high-temperature superconductor (HTSC) photothermoelect rical bolometer. We include dynamics via a small infrared sinusoidal signal incident on the sensitive area of the bolometer. The sensitive area of the bolometer is considered to be approximately mm x mm, with a film thickness in the micron range. This area is a thermoelectrical junction between an H TSC-for example, YBCO-and a high thermoelectic figure of merit material-for example. BiSb-grown on a substrate-for example, Yttria stabilized zirconia (YSZ). The two legs of the thermocouple are connected in a parallel geomet ry. Heat is transferred by direct conductance to the substrate underneath a s well as toward the cold end of the thermojunction-that is, Peltier heat i n the plane of the substrate-is also taken into account. It is found that i f the bolometer is operated under a voltage bias condition, there is substa ntial improvement in the response time and the responsivity of the bolomete r. This appears to be due to the photothermoelectrical operation superimpos ed on the normally used photoelectrical operation.