High Sensitivity and Wide Dynamic Range IR Sensors Based on Electrostrictive Effect in Thin Film Barium Strontium Titanate.

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IR and THz sensors are widely used for monitoring the environment and advancing our understanding of nature. They have many applications in healthcare, public safety, security, and scientific instrumentation. For example, early detection and containment of an outbreak is possible by placing IR imaging systems in hospitals and transportation hubs. IR and THz imaging have also shown great promise in the detection of breast cancer, which is estimated to have caused almost 40,000 deaths in the United States in 2011. Other very important application of IR imaging is visibility enhancement for nighttime driving and reducing road-traffic fatalities. Such systems are also especially critical in the rapidly growing industry of autonomous vehicles. IR imaging is used for the detection of wildfires, firefighting, and determining the conditions of crops. Finally, IR and THz remote sensing offer an effective method to detect chemical and biological agents. In addition, to the direct impact of the proposed research outcomes, there will also be broader impacts associated with the field of acoustic wave devices for wireless communications In spite of the numerous applications, many limitations of currently available IR and THz sensors need to be addressed to fully utilize their potential. The objective of the proposed project is to develop a new class of resonant-type uncooled IR sensor array that employs the electrostrictive properties of thin film ferroelectric barium strontium titanate (BST) to exceed the high performance levels that are traditionally associated with cryogenically cooled photon based IR sensors. The PI proposes to involve undergraduates through the Research Experience for Undergraduates (REU). Collaboration with Michigan?s Summer Undergraduate Research in Engineering (SURE) program will also involve undergraduates from under-represented minorities in this research.The proposed resonant mode IR sensors will utilize the large temperature coefficient of frequency versus impedance, high quality factors, and bias voltage dependent piezoelectric response of optimally designed thin film BST film acoustic wave resonators to achieve room temperature operation, high sensitivity, small pixel area, and high resolution images. The research on novel ferroelectric resonant uncooled IR sensors is based on modeling and simulations, material growth and optimization, fabrication and characterization, and finally evaluation of the sensor for IR detection. The proposed research is transformative as it is expected to pave the way for the development of novel low power, high sensitivity, and highly scalable resonant based IR sensors arrays that surpass performance of the state-of-the-art room temperature IR sensors. The basic principle for thin film BST resonant sensors will also be applicable to the development of sensor arrays operational at THz frequency range.