ELECTRICAL-PROPERTIES OF DOPED POLYPYRROLE SILICON HETEROJUNCTION DIODES AND THEIR RESPONSE TO NOX GAS/

Citation
Ltt. Tuyen et al., ELECTRICAL-PROPERTIES OF DOPED POLYPYRROLE SILICON HETEROJUNCTION DIODES AND THEIR RESPONSE TO NOX GAS/, Thin solid films, 292(1-2), 1997, pp. 293-298
Citations number
23
Categorie Soggetti
Physics, Applied","Material Science","Physics, Condensed Matter
Journal title
ISSN journal
00406090
Volume
292
Issue
1-2
Year of publication
1997
Pages
293 - 298
Database
ISI
SICI code
0040-6090(1997)292:1-2<293:EODPSH>2.0.ZU;2-B
Abstract
The fabrication of a heterojunction between p-doped polypyrrole and p- doped silicon and its possible use in the detecting of nitrogen oxide gas (NOx) is described. Pyrrole was photoelectrochemically polymerized onto a silicon surface from an aqueous solution in the presence of so dium p-toluenesulfonate or p-toluenesulfonic acid. The silicon surface was chemically treated in different ways. Current-voltage characteris tics with regard to the viability of the development as sensor for NOx at room temperature were measured. At low forward bias voltages, the forward currents show standard diode behaviors with diode quality fact ors close to unity. The saturation current densities are of the order of 10(-8) A cm(-2). In the high forward bias voltage region, the heter ojunction diodes exhibit a significant, fast and reversible response t o NOx gas, described by a NOx-induced voltage shift, which corresponds to a NOx-induced decrease in the resistance of the polymer layer. Fur thermore, it was found that the electrical properties of these heteroj unction diodes depend strongly on both the supporting electrolyte used for doping and the chemical treatment of the silicon surface.