J. Phys. Colloques
Volume 48, Numéro C6, Novembre 198734th International Field Emission Symposium / 34ème Symposium International d'Emission de Champ
|Page(s)||C6-239 - C6-244|
J. Phys. Colloques 48 (1987) C6-239-C6-244
THE TEMPERATURE DEPENDENCE OF FIELD EVAPORATION OF GaP (111) SURFACES IN THE PRESENCE OF HYDROGENT. Sakata1, J.H. Block2, M. Naschitzki2 et W.A. Schmidt2
1 Department of Integrated Arts and Sciences, University of Osaka Prefecture, Japan
2 Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-1000 Berlin 33 (Dahlem), F.R.G.
Quantitative measurements on the field evaporation of GaP(111) planes in the presence of hydrogen have been carried out using a field ion microscope. Below room temperature, the evaporation rate was found to decrease with increasing temperature, while above room temperature it steeply increased. The evaporation voltage was found to increase with increasing temperature up to room temperature and decreased slightly with further temperature rising. The evaporation rate war proportional to the hydrogen pressure in the investigated temperature range of 80-330 K. Based on the assumption that surface hydride formation is rate-determining for the field evaporation process, two kinds of hydrogen supply to the kink site atoms of the GaP(111) plane are considered to explain the unusual temperature dependence of the evaporation rates at low temperatures. One supply is only within the (111) plane, and, additionally, the other one is by diffusion over the steps between (111) planes. At T > 300 K the thermally activated evaporation is promoted by hydrogen without having an observable precursor of molecular hydrogen.