Phonon scattering in electron transport phenomena of ITO films

Highly conductive ITO films were prepared by DC magnetron sputtering on glass substrates. Hall measurements of the films were carried out at 6-300 K in order to examine the transport properties of electron carriers in the films. Carrier density of all films studied in this experiment showed degenerate semiconductive behavior. The Hall mobility of as-deposited films exhibited a negative dependence above 150 K on temperature with mu proportional to T-0.1 similar to -0.15. It indicated that the phonon scattering is one of the dominant scattering centers of electron carriers of the film, By oxidation of the films, a decrease in the mobility was observed as well as a lack of the negative dependence. The lack of the negative dependence is attributed to a decrease in the phonon scattering due to a decrease in carrier density, It assumed that doubly charged, interstitial oxygen defects O-i" introduced in grain boundary of the alms preferentially act as charge traps and neutral impurity defects ((SnIn2Oi)-O-.") act as carrier scattering centers. (C) 2000 Elsevier Science Ltd. All rights reserved.