PHOTOEMISSION ELECTRON-MICROSCOPY STUDIES OF PT GAP(001) BURIED INTERFACES/

Using (secondary) photoelectron emission microscopy, we studied the fu lly formed 80 Angstrom Pt/n-GaP(001) interface with a lateral resoluti on better than 2 mu m. We probed the chemically etched and sulfur pass ivated GaP(001) surface by ultraviolet and soft x rays. The radiation source was either a deuterium lamp or the radiation from ELETTRA's U12 .5 undulator. Due to their escape depth, the photoemitted secondary el ectrons carry chemical information of buried interfaces. The use of tu nable synchrotron radiation enabled us to obtain chemical contrast by digital subtraction of the microimages taken at photon energies above and below each core-level absorption edge. The microimages revealed la teral changes in photoyield efficiency and chemical composition. The r esults were confirmed by x-ray photoemission spectromicroscopy measure ments performed using A1 K alpha radiation. (C) 1996 American Institut e of Physics.