Electrical resistivity reduction and spatial homogenization of Ga-doped ZnO film by Zn layer insertion

Ga-doped ZnO (GZO) films inserted with a Zn layer were deposited at room temperature by a sputtering method to decrease carrier-compensating defects. The Zn-inserted GZO films showed a resistivity decrease resulting from an increase in carrier density. The carrier density further increased by thermal annealing and showed a maximum at around 400 degrees C. The formation of a SiO2 capping layer on the film surfaces enhanced the carrier density at temperatures higher than 400 degrees C, resulting in a lowered resistivity to 3.3 x 10(-4) Omega cm for a 200-nm-thick film. In addition, resistivity degradation that was induced at the erosion position in the sputtering deposition process disappeared. The increase in carrier density, decrease in resistivity, and homogenization of the electrical property indicate that carrier-compensating crystalline defects such as the zinc vacancy induced in Ga-doped ZnO films during the deposition process are decreased by the Zn enrichment