Uncooled LWIR Thermal Imaging Using Schottky Diodes

Solid State Scientific Corporation (SSSC) has developed the theory of operation for the Thermonic Thermal Detector (TTD) for uncooled infrared sensing of 8 to 14 um radiation based on a schottky diode sensing element. In addition, SSSC has fabricated sample detectors with electrical characteristics that correspond to an NEDT of 6 mK, if integrated with a state of the art microbolometer multiplexer. The predicted NEDT of the TTD is thus 7 times more sensitive than the current state of the art VOx microbolometer. The thermionic thermal detector is a new type of device whose operation is not related to classic photoemissive Schottky diode photon detectors. The TTD operates uncooled with the individual elements thermally isolated (as in a microbolometer), and uses a reverse bias Schottky diode as the sensing element. For a fixed bias voltage and Schottky barrier height, the magnitude of the reverse bias current from the diode is a measure of the diode temperature. Since the reverse bias current is a Schottky diode is exponentially dependent on the temperature of the detector, it has a high temperature coefficient.