A novel probe for near field optical microscopy based on luminescent silicon

Abstract A porous silicon (PS) based tip has been developed as a small light emitting probe for scanning near field optical microscopy (SNOM). Another possible application is photoresist patterning on the micrometer and nanometer scale, where dimensions ∼ 100 nm are required for extending conventional lithographic processes. In principal light emission can be excited optically in fluorescence as well as electrically by an applied bias voltage. We show the mechanical fabrication of a luminescent probe at the apex of a conventional STM tip and its use to record initial NFO images of micron-sized test structures. The sensor has been characterized by life time measurements and shows its stability over more than thousand minutes. Its quantum efficiency has been measured to range from 0.025 to 0.14 depending on the excitation photon rate and is found to increase with small size of the particles. The emission power with the present set-up is 7 × 10 −11 W at 630 nm under an Ar + laser (488) nm excitation at room temperature. Additionally high frequency plasma etching has been used to fabricate conventional Si atomic force microscopy (AFM) cantilevers with a PS luminescent tip which can be used simultaneously for AFM and SNOM measurements. We present design studies for the fabrication of integrated tips suitable for simultaneous AFM, STM and SNOM measurements.