Properties of Ga-doped ZnO films

Transparent conductive films of Ga-doped ZnO (GZO) were deposited on glass substrates by de magnetron sputtering using a ZnO target with Ga2O3 content of 3 to 10 wt%. The dependence of electrical properties on substrate temperature, Ga2O3 contents in the sputtering target and magnetic field strength at the target surface were investigated. It was found that the resistivity depended on both substrate temperature and Ga2O3 content. At substrate temperatures of 100 degrees C, resistivity decreased with increasing Ga2O3 content and 6.5 x 10(-4) Omega cm was obtained for a Ga2O3 content of 7.5-10.0 wt%. When the substrate temperature was increased to 300 degrees C, GZO films deposited using 4.5 to 5.7 wt% Ga2O3 targets had a resistivity of 2.7 x 10(-4) Omega scm. In addition, the resistivity was found to decrease with increasing magnetic field strength. When the substrate temperature and Ga2O3 content were 100 degrees C and 7.5 wt%, respectively, the resistivity decreased from 6.5 x 10(-4) to 2.9 x 10(-4) Omega cm by increasing the magnetic field strength from 3.0 x 10(-2) to 6.5 x 10(-2) T. The minimum resistivity of 2.2 x 10(-4) Omega cm was obtained at 250 degrees C (Ga2O3 content:5.7 wt%) for a magnetic field strength of 6.5 x 10(-2) T. The decrease in resistivity was due to the increase both in carrier concentration and mobility. (C) 1997 Elsevier Science B.V.