SCANNING PHOTOELECTRON SPECTROMICROSCOPE BASED ON COHERENT VACUUM ULTRAVIOLET-RADIATION

Design and performance of a newly developed scanning photoelectron microscope based on focused coherent vacuum ultraviolet (VUV) light are described. The VUV light at 118 nm wavelength (10.48 eV photon energy) was generated by the frequency upconversion of a pulsed YAG laser light. The microscope is characterized by its high spatial resolution of a few microns, which is consistent with its high-energy resolution of better than 200 meV. The spatial resolution was provided by focusing the VUV light nearly to its diffraction limit, while the photoelectron energy was resolved by a high efficiency time-of-flight (TOF) energy analyzer. The point-to-point data acquisition, as well as the sample scanning, were controlled by a computer system, and the spectral data were accumulated at every two-dimensional mesh point of the specimen. From the photoemission profile across a processed Ag/Si stripe, the spatial resolution was nominally 6-mu-m. The energy resolving capability of the present microscope was demonstrated by the observation of crystalline facets formed on a polished copper disk.