Uncooled Infrared Detectors

Donald P. Butler, Professor

YBCO Uncooled Infrared Detectors

A radiation detector is a device that produces an output signal, which depends on the amount of radiation hitting the active region of the detector. In general, infrared sensors can be classified as thermal or photon type of detectors. Photon type detectors such as photovoltaic or photoconductive sensors operate on the principles of direct electron - photon interaction. They provide superior sensitivity and response speed. However, Photon detectors typically require costly cryogenic operation to minimize the noise sources to obtain the high relative sensitivity. On the other hand, thermal detectors convert incident radiation into heat, thereby raising the temperature of the detector element. This change in temperature is then converted to an electrical signal that can be amplified and displayed. Thermal detectors are capable of responding to a wide range of wavelengths without appreciable variation in responsivity. Thermal detectors display high sensitivity at room temperature to permit imaging and radiometry applications.

There are 3 primary types of thermal detectors: bolometers whose resistance changes with temperature, pyroelectric detectors where the spontaneous polarization or surface charge changes with temperature, and thermopile detectors that utilize the Seebeck or thermoelectric effect.

Research at UTA has the following focus:

The investigation of semiconducting Y-Ba-Cu-O as a new material for uncooled microbolometer applications

The investigation of ferroelectric and pyroelectric properties in Y-Ba-Cu-O

The investigation of noise mechanisms in uncooled infrared detectors

Novel micromachined structures for uncooled infrared detectors.

SEM micrograph of 40 mm x 40 mm self-supporting Y-Ba-Cu-O microbolometers with Ti electrode arms and Au contacts. The detectors were micromachined using a standard polyimide sacrificial layer.