OPTICAL NEAR-FIELD IMAGING USING THE KELVIN PROBE TECHNIQUE

in the farce detection of the evanescent field using a semiconductor t ip, the force gradient is affected not only by the surface potential c hange due to the evanescent field, but also by the contact potential d ifference (CPD) between the tip and the sample which is not uniform on the surface. In this paper, we propose a novel method to measure the evanescent field without the CPD effect using the Kelvin probe techniq ue. Simultaneous ima es of the topography, the CPD and the force gradi ent due to the evanescent held were obtained on a 15-nm thickness sput tered Au surface. These images showed no correlation in several areas. The lateral resolution of the force gradient due to the evanescent fi eld was better than 15 nm (lambda/33).