Tunneling atomic force microscopy (TUNA) is used to identify leakage current characteristics in SiO2 doped ZrO2 thin films within the nanometer scale. TUNA current maps and local TUNA I-V curves provide similar tendencies such as conventional macroscopic I-V curves concerning the dependence of leakage current on thickness and doping level. However, microscopic data additionally visualize the influence of minimal deviations in composition or morphology on the electrical film homogeneity not observable by macroscopic techniques. Therefore, optimization of the SiO2 dopant concentration in ZrO2 is possible. Additionally, information regarding the nonuniformity of charge trapping can be obtained out of local TUNA I-V curves implying the broad potential of TUNA. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3058725]