Pyroelectric detector of infrared radiation for ecology

Year: 2005

Jiří Zelinka, MSc.; Fedor Šrobár, DSc.; Zdislava Podvalová, MSc.

For quite a long period we studied preparation methods and physical properties of single crystals of organic/inorganic substances belonging to the triglycine sulfate (TGS]) family. The crystals exhibit spontaneous electric polarization and their surface charge varies with changing temperature. This so-called pyroelectric phenomenon affords detection of small temperature differences, such as those caused by absorbed infrared radiation. To be applicable for the construction of good infrared detectors, the crystals must satisfy a number of demanding criteria. For this purpose we built a special laboratory for the growth and characterization of high-quality TGS single crystals. In cooperation with the prospective user (Tesla Blatná, Inc.), properly oriented wafers cut from the crystals were processed into infrared detector chips and subsequently encapsulated to yield detector devices. Since the prices of similar detectors on the world markets are quite high, their domestic mass production would be economically attractive.

In cooperation with Tesla Blatná, Inc., a laboratory pyroelectric carbon dioxide detector was constructed on the basis of TGS single crystals doped with D-phenylalanine and tetravalent platinum. First results demonstrated the capability of the measurement of CO2 concentrations in the atmosphere with an accuracy of 3 per cent.

1. J. Novotný, Z. Podvalová, J. Zelinka: „Growth of triglycine sulfate single crystals doped with Pt(IV) and L-alanine.“ Crystal Growth and Design 3, 393-395, 2003.
2. J. Novotný, B. Březina, J. Zelinka: „Growth and characterization of TGS and DTGS single crystals doped with Pt(II), Pt(IV), and L-alanine.” Cryst. Res. Technol. 39, 1089-1098, 2004.
3. J. Novotný, J. Zelinka, Z. Podvalová: “Growth and characterization of TGS single crystals doped with D-phenylalanine and Pt(IV) ions.” Ferroelectrics 312, 1-6, 2004.
4. J. Novotný, J. Zelinka, F. Moravec:”Broadband infrared detectors on the basis of PATGS/Pt(IV) single crystals.” Sensors and Actuators A119, 300-304, 2005.
5. J. Novotný, J. Zelinka: “Hysteresis phenomena in doped TGS crystals.” 5th Int. Symp. on Hysteresis Modeling and Micromagnetics. Budapest 2005. Book of Abstracts pp. 116-117.
6. J. Zelinka: Application of a TGS pyroelectric sensor in an experimental gas analyzer. IREE Research Report No. Z-2096/A, 2005 (in Czech).
7. F. Šrobár: „Topology of feedback in the theory of molecular field.“ Physica B (Condensed matter) 371, 2006, in print.