P2 - Semiconducting Polymer Compounds as Sensitive Layer for Bolometric Applications

Event
SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Nürnberg
Band
Proceedings IRS² 2011
Chapter
IP - Poster Session
Author(s)
A. Nocke, M. Wolf, H. Budzier, G. Gerlach, K. Arndt - Technische Universität Dresden (Germany)
Pages
103 - 108
DOI
10.5162/irs11/ip2
ISBN
978-3-9810993-9-3
Price
free

Abstract

Our work investigates the ability to integrate conductive polymer compounds as self-supporting sensitive layers in microbolometers. Therefore, an appropriate technology was developed, including a sacrificial layer technique and a dielectrophoretic alignment procedure of the semiconducting filler particles. The polymer matrix causes mechanical stability of the compound and can be technologically modified using standard polymer processes. The aligned filler material forms an electrically conducting network in the polymer matrix with a temperature coefficient of resistance (TCR) that yield the bolometric effect. The particle alignment allows the usage of significantly reduced amount of filler in contrast to non-aligned polymer compounds, which is advantageous for the other process steps. Investigated fillers are the semiconducting materials tellurium and vanadium dioxide (VO2).

Tellurium has a band gap of 0.33 eV causing a bulk material TCR-value of -2.3 %/K at room temperature. It can be easily chemically synthesized and grows in elongated form due to its crystallographic characteristics. The size and aspect ratio of the resulting rods can be tailored by the synthesis parameters. Used tellurium rods have an average diameter of 250 nm and an average length of 5 μm.

The band gap of the semiconducting phase of VO2 at room temperature ranges between (0.6…0.7) eV. This leads to TCR-values of (4.0…4.8) %/K for bulk material at room temperature. Crystalline VO2- particles under investigation have a size distribution of (0.5…2) μm.

The electrical properties of the sensitive compounds are discussed: In comparison to the tellurium compound the VO2-compound has improved noise characteristics, a higher TCR-value and a greater resistance leading to a higher detectivity.

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