Transmission scanning near-field optical microscopy with uncoated silicon tips

In this paper we report on the implementation of an uncoated silicon (Si) cantilever probe into a transmission scanning near-field optical microscopy (SNOM) architecture. In a first stage, the expected transmission behaviour of a sharp silicon probe is investigated by calculating the complete electric field distribution both inside and outside a silicon tip facing a sample. Experimental applications using near-infrared radiation λ = 1.06 μm) are then proposed. In particular, compact disc features (Ax ≤ 1 μm) were imaged successfully with our setup (lateral resolution: better than 250 nm). Furthermore, when dealing with finer sample structures (Δx ≤ 100 nm), topography artifacts were clearly evidenced. The resulting highly resolved images of nanostructures are to be attributed to some interference effects occurring between the illuminated probe and the sample.