J. Phys. Colloques
Volume 47, Numéro C2, Mars 198632 nd International Field Emission Symposium / 32ème Symposium International d'Emission de Champ
|Page(s)||C2-303 - C2-308|
J. Phys. Colloques 47 (1986) C2-303-C2-308
PULSED-LASER ATOM-PROBE STUDY OF Si, GaAs AND GaPO. NISHIKAWA, E. NOMURA, M. YANAGISAWA et M. NAGAI
Department of Materials Science and Engineering, The Graduate School at Nagatsuta, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 227, Japan
Si, GaAs and GaP were mass analyzed by the pulsed-laser energy-forcusing atom-probe. More than 30% of Si atoms were detected as clusters of up to Si10. The number of singly charged clusters is larger than that of doubly charged clusters. No Si22+ and quadruply charged clusters were observed possibly due to the dissociation of densely charged ions by the Coulomb repulsive force. Although the stoichiometric compositions of GaAs and GaP were obtained, the composition of GaP appeared to vary with tip voltage. Most Ga and P atoms were detected as cluster ions and the size of the most abundant cluster shifts to the smaller side as the tip voltage increases. Laser-stimulated diffusion of surface atoms and the preferential field evaporation of Ga might be playing a key roll for the observed results.