EDP Sciences Journals List
Home Document
Subscriber Authentication Point
Issue Eur. Phys. J. Appl. Phys.
Volume 18, Number 1, April 2002
Page(s) 9 - 15
Section Surfaces, Thin Foils and Nanomaterials
DOI 10.1051/epjap:2002021



Eur. Phys. J. AP 18, 9-15 (2002)
DOI: 10.1051/epjap:2002021

Unusual high sensitivity in highly oriented laser ablated thin films of $\mathsf{SnO_2}$ on (1102) sapphire and (100) $\mathsf{LaAlO_3}$

K.I. Gnanasekar1, B. Rambabu1 and K.C. Langry2

1  Surface Science, Spectroscopy and Solid State Ionics Laboratory, Department of Physics, Southern University and A&M College, Baton Rouge, Louisiana 70813, USA
2  Chemical and Biological Detection Group, Lawrence Livermore National Laboratory, Livermore, California 94550, USA

Rambabu@grant.phys.subr.edu

(Received: 28 April 2001 / Received in final form: 15 November 2001 / Accepted: 17 December 2001)

Abstract
A systematic investigation on growth and sensor characteristics of SnO 2 thin films of different orientations is reported for the first time. Thin films were grown by pulsed laser (KrF; $\lambda=248$ nm) ablation technique under in-situ conditions. Films deposited at 525 °C on (1102) sapphire were predominantly (101) orientated whereas those deposited on (100) LaAlO 3 were highly a-axis orientated. Sensors made of predominantly (101) oriented films exhibited more than two orders magnitude change in resistance even for 100 ppm of H 2 in air at 310 °C. The response and retracing times of the sensor were remarkably short respectively 30 and 200 s. Sensors made of a-axis oriented films also exhibited similar sensitivity and response time for the same quantity of both H 2 and LPG. However, the retrace time was very long typically about 20 min. Atomic force microscopic (AFM) investigation reveals that the films are highly granular with an average size of about 100-150 nm which is ten times larger than the critical size of 6 nm, a criterion required for high sensitivity. (The Debye length of ${\rm SnO}_2 \cong 3.07$  nm at 293 K and the critical grain size is therefore $2~\times$ Debye length, which is 6 nm.)

PACS
07.07.Df - Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing.
81.15.Fg - Laser deposition.
73.61.Jc - Amorphous semiconductors; glasses.


© EDP Sciences 2002


What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.