Correlated piezoelectric and electrical properties in individual ZnO nanorods

Resistivity and piezoelectric response of individual ZnO nanorods were measured using scanning force microscopy. We found a variation in resistivity of 3 orders of magnitude, from 0.1 to 155 Omega cm and in piezoelectric coefficient ranging from 0.4 to 9.5 pm/V in ZnO nanorods grown from solution at the same time on the same substrate. However, there exists a clear correlation between these two properties: nanorods with low piezoelectric response display low resistivity. The relationship is explained by the reduction of the Madelung constant due to free electrons. The results highlight that slight differences in the local environment during synthesis can cause large variation in physical properties found among similar nanostructures. These variations cannot be revealed through ensemble measurements and may contribute to the confusion in the literature of individual nanostructure properties. We demonstrate that correlating multiple physical properties on individual nanostructures provides an insight into the origin of the varying physical properties.