Sn 1-x VxOy thin films deposited by pulsed laser ablation for gas sensing devices
Abstract
Polycrystalline pure and V-doped SnO2 thin films have been prepare by pulsed laser deposition (PLD) on Si substrates, with a Si3Ni4 buffered layer. PLD technique, under proper conditions, has probed to produce nanocrystalline-structured materials, which are suitable for gas sensing. In this work we analyze the role of V doping in the structural properties and in the electrical conductivity of the films. The deposition temperature was fixed at 600 degrees C and the films were grown in oxygen atmosphere. The films resulted nanocrystalline with 50 to 120 nm average grain size connected by necks with high surface areas. The microstructural and electronic properties of all the films were analyzed using scanning-electron microscopy, x-ray diffraction and conversion electron Moessbauer spectroscopy. Electrical conductance in a dynamic regime in dry synthetic air has been evaluated as a function of temperature. Moessbauer spectra reveal the presence of 15 percent of Sn2+ in the 5at. percent V-doped films. At about 340 degrees C, a strong increase in the conductivity of the films occurs. Possible explanations are that thermal energy could excite electrons from the vanadium ions into the crystal's conduction band or promotes the diffusion of surface oxygen vacancies towards the bulk, increasing strongly the conductivity of the film.
- Publication:
-
ALT 1999 International Conference on Advanced Laser Technologies
- Pub Date:
- February 2000
- DOI:
- 10.1117/12.378173
- Bibcode:
- 2000SPIE.4070..312D