Conducting atomic force microscopy was utilized to study the nanoscale surface electrical properties of N-doped zinc oxide films that had been prepared by pulsed laser deposition at different substrate temperatures. Current-voltage measurements were made while the conducting tip was fixed at different contact current points after scanning for normal imaging. Experimental results indicated that changes in the substrate temperature caused the redistribution of n-type carrier (Ohmic contact) and p-type carrier (Schottky contact) regions on the surface. Such a microscopic measurement method can be adopted to observe precisely the variances in the local carriers on the surface of films, benefiting future studies of nanoscale p-n homojunctions.