This paper reviews deposition, integration, and device fabrication of PbZr/sub x/Ti/sub 1-x/O/sub 3/ (PZT) films for applications in micro-electromechanical systems. An ultrasonic micromotor is described as an example. A summary of the published data on piezoelectric properties is given. The figures of merit for various applications are discussed. Some considerations and results on operation, reliability, and depolarization of PZT thin films are presented. The state of the art allows some preliminary conclusions.

PZT thin films for microsensors and actuators: Where do we stand?

The state of the art of thin-film pyroelectric infrared (IR) detectors is reviewed covering device physics, material performance, micro-fabrication and device examples. Emphasis is given to special issues related to thin films, such as small heat capacities and the substrate influence on the pyroelectric properties. For the latter, an overview of the hitherto reported values is given. Examples of micromachined IR detectors based on pyroelectric thin films are described. The ultimate limit of micromachined thermal IR detectors is estimated for uncooled operation. It is concluded that the best pyroelectric thin films achieved to date are in principle sufficiently good to approach this limit, meaning that the present performance of pyroelectric thin-film focal plane arrays can still be improved by more than a factor of 10. A comparison of the different principles for IR detection shows that pyroelectricity is indeed one of the most competitive principles for uncooled IR detection. The major obstacle hindering quick industrialization is the fabrication complexity.

https://iopscience.iop.org/article/10.1088/0034-4885/64/10/203/pdf

Micromachined infrared detectors based on pyroelectric thin films

An infrared imager includes an array of capacitance sensors that operate at room temperature. Each infrared capacitance sensor includes a deflectable first plate which expands due to absorbed thermal radiation relative to a non-deflectable second plate. In one embodiment each infrared capacitance sensor is composed of a bi-material strip which changes the position of one plate of a sensing capacitor in response to temperature changes due to absorbed incident thermal radiation. The bi-material strip is composed of two materials with a large difference in thermal expansion coefficients.

Infrared imager using room temperature capacitance sensor

Methods and apparatus for compensating a radiation sensor for ambient temperature variations. Ambient temperature variations may produce undesirable artifacts in electronic signals output by a radiation sensor. In some cases, such artifacts may detrimentally reduce the dynamic range of the sensor and/or processing circuitry associated with the sensor with respect to radiation of interest. The radiation sensor may be compensated for such undesirable artifacts by, for example, adding an appropriate offset to a sensor bias voltage or a sensor bias current, and/or controlling a temperature of the radiation sensor, based on variations in the ambient temperature.

Method and apparatus for compensating a radiation sensor for ambient temperature variations

A thermal infrared detector comprising a dielectric pellicle (5) suspended over a cavity in a substrate (6), the pellicle supporting a detector element (1) comprising a heat sensitive semiconductor layer (3) between a pair of thin film metallic contacts (2, 4), these being deposited on the pellicle, the cavity being formed by etching and removal of the substrate material through holes or slots (8) in the surface of the substrate.

Semiconductor film bolometer thermal infrared detector

A thin film pyroelectric imaging array (N, M) fabricated as a Si wafer. A thin film (40) of PbTiO3 is deposited on a thermally isolated bridge (45). The bridge (45) suspends the PbTiO3 sensor (40) over a preferentially etched cavity (70) in the Si wafer (10). Improved thermal isolation increases the responsivity of the sensor (33) to incident radiation. The pyroelectric sensor (33) formed can operate effectively at room temperature.

Thin film pyroelectric imaging array.

A photon detector based upon photon-assisted tunneling in superconductor-insulator-superconductor or super-Schottky structures, in which the superconductor is a high transition temperature superconductor. An electrical bias is provided on either side of such structures so that photo-assisted tunneling, in the presence of incident photons on the structure, can occur to thereby permit a tunneling current therebetween.

Wavelength tunable infrared detector based upon super-schottky or superconductor-insulator-superconductor structures employing high transition temperature superconductors

Disclosed are cascaded spin-flip Raman lasers involving alloy semiconductors such as mercury cadmium telluride with different energy gaps or with an energy gap gradient to provide for a relatively large change in frequency for a small change in field and enabling operation at low magnetic field levels where the output power and conversion efficiency are high.

Jr. Paul W. Kruse

Papers

Thin film pyroelectric imaging array.

Wavelength tunable infrared detector based upon super-schottky or superconductor-insulator-superconductor structures employing high transition temperature superconductors

Spin-flip raman laser with increased tuning range and increased efficiency