| Quantum mechanical electron tunneling between a pair of metal electrodes was first used in the scanning tunneling microscope (STM). In this device, the piezoelectric feedback control voltage necessary to maintain a constant tunneling gap between a sharp tip and a sample is recorded and used to develop a topographical image of the sample surface. In recent years, this phenomenon has been successfully used as a sensitive displacement transducer in miniaturized accelerometers, magnetometers and infrared detectors. An advantage of tunneling over other displacement transducers is that it can be scaled down in size without reduction in displacement resolution. About the tunneling point, tunneling transducers are capable of displacement sensitivities of up to 1nA/Å. Since it is possible to measure and regulate tunneling currents far less than 1nA, based on operating parameters, tunneling displacement transducers can detect variations in electrode separation smaller than 1mÅ. Due to the highly non-linear tunneling current-displacement relationship, tunneling transducers are always used with feedback control to maintain a working separation of a few Angstroms.; The first micromachined tunneling infrared detectors based on the Golay cell were made at the Jet Propulsion Laboratory (JPL). In this device, deflection of a flexible membrane, due to thermal expansion of trapped air caused by infrared illumination was detected through the use of tunneling displacement transducers. The sensors produced have performance characteristics that are comparable to the best uncooled infrared detectors around, however the sensors were hand assembled and therefore had inconsistent operating parameters. For example, there could be a difference in operating voltage of hundreds of volts between two detectors made from the same set of wafers. Also, due to the fact that the detectors were hand assembled, yield was poor.; The sensors featured in this work have comparable performance characteristics to early tunneling sensors, but are made using a wafer-scale batch fabrication process. The sensors produced have uniform operating parameters, consistent with design goals, and were produced with high yield (∼80%). In addition, work was done to improve the performance of the feedback controller used in operating the sensor.; This dissertation describes the fabrication, modeling and performance characterization of the devices produced, experimental data is presented, and a performance comparison is made with existing uncooled thermal infrared detectors of similar dimensions. |
