Effect of Doping Concentration on the Thermolectric Properties of Nano Ga-doped ZnO Films

Nano Ga-doped ZnO(GZO) thin films with different Ga doping concentration (1, 3, 5, 7at%) were deposited on glass substrate by RF magnetron sputtering. The influence of Ga doping concentration on the microstructure, morphology and thermoelectric properties of GZO films was investigated. It is found that all the films are polycrystalline with C-axis preferred orientation, the crystal size are 22, 15, 24 and 27nm for the films deposited at the Ga content of lat.%, 3at.%, 5at.% and 7at.%, respectively. The thermoeletromotive force (thermo-emf) change linearly with temperature difference, implying that Seebeck effect can be apparently observed in GZO films. The thermo-emf are negative, the Seebeck coefficient is about -58, -20, -30 and -25 mu V/K for samples with Ga doping concentration at 1 at%, 3 at%, 5 at%, 7at%, respectively. The power factor is (2.78 similar to 12.79) x 10(-5)W/K(2)m for our thin films.