J. Phys. Colloques
Volume 47, Numéro C2, Mars 198632 nd International Field Emission Symposium / 32ème Symposium International d'Emission de Champ
|Page(s)||C2-297 - C2-302|
J. Phys. Colloques 47 (1986) C2-297-C2-302
MASS ANALYSIS OF GaAs AND GaP BY THE COMBINED ATOM-PROBEO. NISHIKAWA, E. NOMURA, H. KAWADA et K. OIDA
Department of Materials Science and Engineering, The Graduate School at Nagatsuta, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 227, Japan
A time-of-flight atom-probe with straight and deflected flight paths was constructed. One section of the outer electrode of the Poschenrieder type deflector is formed by 3 mm apart parallel W wires of 0.3 mm in diameter to pass straightly flying ions. The distribution of ion energy examined by the straight path A-P indicates the evaporation of slow ions with low energies. The adjustment of the voltages of the deflector electrodes to let the slow ions pass through the deflector made possible to obtain the stoichiometric composition of GaAs but not of GaP because the energy of Ga ions evaporated from GaP was significantly lower than that of P. Accordingly the erroneous composition of GaAs and GaP observed by the A-P analysis is the result of the preferential field evaporation of unstabilized Ga atoms due to the evaporation of nearby surface atoms, possibly As and P.