Discipline: Physics
Subcategory: Physics (not Nanoscience)
Jessica Patel - Delaware State University
Co-Author(s): Bakare O'neil, Nicholas Calvano, and Mukti Rana, Delaware State University, DE
Since the discovery of thermal radiation beyond the visible spectrum in the year 1800, the field of thermal detection has been expanded in the optical field. This has led to a very diverse array of scientific tools used to study and observe the spectrum beyond visible light. Pyroelectric detectors are one of these tools which has a spontaneous polarization when there is a change in temperature in range of its sensors. The spontaneous polarization occurs when infrared radiation is absorbed and produces a voltage. Pyroelectric detectors are used in uncooled infrared detection for night vision cameras, radometric and other handheld devices for defense and security, surveilences, firefigting operations, driver’s aid and many other applications. This work depicts the characterization and deposition of calcium modified lead titatante (Pb1-xCaxTiO3, PCT) thin films for use as pyroelectric infrared (PIR) detectors. Using an RF sputter system at room temperature in an Ar:O2 filled chamber, the films were deposited. Annealing was performed at 450, 500, 550 and 600 ºC in an O2 rich environment and soaked for 15 minutes. Energy dispersive spectroscopy (EDS) was conducted to obtain the atomic composition of the PCT films. Au electrodes were sputtered on the PCT thin films and lifted off to form the capacitors. The capacitance, loss tangent, pyroelectric voltage and current were measured between the temperature range of 303 K to 353 K. Films annealed at 550 ºC showed the highest value of pyroelectric current and coefficient, 2.45 × 10-12 A and 1.99 μC/m2K at room temperature. Loss tangent showed minutiae variances for all anealled PCT samples. The films were multi-crystalline oriented in <100>, <111>, and <200> as proven by x-ray diffraction (XRD). Future study is needed to fully characterize the optical properties while varying the fabrication varibles such as chamber pressure, deposition temperature and gas mixtures for reactive sputtering and annealing temperature and time. References: Nagarbawadi M. A., Jangade P. S. and Bagwan S. T., “The influence of Calcium doping on structural and electrical properties of ferroelectric Lead Titanate ceramics”, IOSR Journal of Applied Physics, 15-19, (2014). Chopra S., Sharma S., Goel T. C and Mendiratta R. G., “Effect of annealing temperature on microstructure of chemically deposited calcium modified lead titanate thin films” Applied Surface Science 230, 207-214, (2004). Tang X. G., Chan H. L. W. and Ding A. L., “Electrical properties of compositionally graded lead calcium titanate thin films”, Solid State Communications 127, 625-628, (2003). Pontes D.S.L, Leite E.R., Pontes F.M., Longo E. and Varela J.A., “Microstructural, dielectric, and ferroelectric properties of calcium-modified lead titanate thin films derived by chemical processes”, Journal of European Ceramic Society 21, 1107-1114, (2001).
Funder Acknowledgement(s): This work is partially supported by US Department of Navy Grant # N0014-15-1-2812, National Science Foundation Grant # MRI-1427089 and National Aeronautics and Space Administration Grant # NNX15AP84A. The authors would like to thank Philip Chrostosky for his help.
Faculty Advisor: Mukti Rana, mrana@desu.edu
Role: I performed some experimentation and analysis under the guidance of graduate students and my adviser.