Gas sensing properties of epitaxial SnO2 thin films prepared by atomic layer deposition

• Published in: Sensors and actuators. B, Chemical Vol. 93; no. 1-3; pp. 552 - 555
• Main Authors: Rosental, A., Tarre, A., Gerst, A., Sundqvist, J., Hårsta, A., Aidla, A., Aarik, J., Sammelselg, V., Uustare, T.
• Format: Journal Article
• Language: English
• Published: 01.08.2003
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/S0925-4005(03)00236-3

Undoped SnO 2 thin films are grown on α-Al 2 O 3 (0 1 2) ( r -cut sapphire) substrates by gas phase atomic layer deposition (ALD). Two precursor pairs, SnI 4 –O 2 and SnCl 4 –H 2 O 2 , both new for ALD, are used. The films have a cassiterite structure and are (1 0 1)[0 1 0] cassiterite ||(0 1 2)[1 0 0] sapphire oriented. A good epitaxial quality and the conductivity acceptable from the standpoint of semiconductor gas sensors are achieved for ultrathin films grown from SnI 4 –O 2 at 600 °C. The sensitivity of these films to CO in air has a maximum at a thickness of about 10 nm. Response rise and decay times belonging to a several seconds interval are measured. The films are assumed to function as a single grain.