PROPERTIES OF GA-DOPED ZNO FILMS

Transparent conductive films of Ga-doped ZnO (GZO) were deposited on g lass substrates by de magnetron sputtering using a ZnO target with Ga2 O3 content of 3 to 10 wt%. The dependence of electrical properties on substrate temperature, Ga2O3 contents in the sputtering target and mag netic field strength at the target surface were investigated. It was f ound that the resistivity depended on both substrate temperature and G a2O3 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 tempe rature was increased to 300 degrees C, GZO films deposited using 4.5 t o 5.7 wt% Ga2O3 targets had a resistivity of 2.7 x 10(-4) Omega scm. I n addition, the resistivity was found to decrease with increasing magn etic field strength. When the substrate temperature and Ga2O3 content were 100 degrees C and 7.5 wt%, respectively, the resistivity decrease d from 6.5 x 10(-4) to 2.9 x 10(-4) Omega cm by increasing the magneti c field strength from 3.0 x 10(-2) to 6.5 x 10(-2) T. The minimum resi stivity 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 concen tration and mobility. (C) 1997 Elsevier Science B.V.