Influences of thermal desorption of Zn atoms on electrical and optical properties of Ga-doped ZnO (GZO) films deposited by ion plating with direct current arc discharge have been studied. The amount of Zn desorption was controlled by thermal desorption spectroscopy. The resistivity of the GZO films was not affected by the thermal desorption of Zn up to the heating temperature of 300 degrees C, however, the carrier concentration and the Hall mobility showed remarkable changes. The carrier concentrations decreased with increasing the Zn desorption, and the Hall mobility increased. The decrease in carrier concentration showed strong correlation with the desorption of Zn atoms from the GZO films. The transparency in near infrared wavelength region increased without change of resistivity due to the decrease in carrier concentration. (C) 2011 Elsevier B.V. All rights reserved.