Electron scattering mechanisms in ITGO (Sn+Ge doped In₂O₃) thin films for low emittance window coatings

CPMOH, Université de Bordeaux I, 351 Cours de la Libération, 33405 Talence Cedex, France

Corresponding author: jsalarde@cribx1.u-bordeaux.fr

Received: 27 May 1998
Accepted: 3 July 1998
Published online: 15 September 1998

Abstract

Electronic properties of ITGO (Sn+Ge doped In₂O₃) thin films have been investigated for various compositions with decreasing doping levels (molar ratios [Sn]/[In] ≤ 0.05 with [Ge] = 0.2 [Sn]). Conductivity and Hall measurements versus temperatures ranging from 77 to 500 K have shown that two electron scattering mechanisms are to be considered. Even though ionised impurities dominate the electron scattering in the whole temperature range, the influence of optical phonons cannot be neglected. It appears gradually from 200 to 250 K and involves a marked decrease of the electron mobility with temperature. The influence of the doping level on the electron mobility has also been studied. It can be correlated with the effective mass variations deduced from the evolution of the thermoelectric power versus temperature [1, 2] and with the observation by optical absorption of localised states for the lowest doping levels [1, 8].