Advanced Oxide Materials and Devices Project Leader: Alex Ignatiev at ignatiev@uh.edu
Task Leader: Professor Nai Juan Wu at naijwu@uh.edu

Ferroelectric thin films, with their strong pyroelectric behavior, are currently being developed for uncooled infrared detector and thermal imaging applications. These include both military and commercial uses, ranging from night vision and surveillance to process control. Epitaxial doped-PbZrTiO₃ (PZT) films grown by pulsed laser deposition (PLD) have been integrated with silicon through the use of conducting oxide electrodes and buffer layers. YBa₂Cu₃O_7-x (YBCO) films have been used at room temperature as conducting oxide electrodes, as well as an excellent template layer for epitaxial growth of the doped PZT thin films. The high infrared reflectivity and low thermal conductivity of YBCO layers are effective in increasing the detector's performance, and the epitaxial character of the films improves the pyroelectric figures of merit F_v and F_d. The integration to silicon incorporates a yttria-stabilized zirconia (YSZ) buffer layer resulting in a heterostructure detector with high detectivity of ~5 x 10⁸ cmHz^1/2/W over the wavelength range of 1 mm to 20 mm. Additional sensitivity enhancement is obtained through the development of YBCO microbridges on the YSZ/Si substrate. The air gap in the microbridge structure effectively reduces the thermal mass of the PZT detector and results in a three-fold increase in photoresponse in the modulation frequency range of 20 to 50 Hz.

Personnel: Dr. YuQing Xu: Senior Research Scientist Yanqi Wang: Research Assistant Wilfredo More: Postdoctoral Associate

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