Surface reactions on beryllium after carbon vapour deposition and thermal treatment

Surface reactions and carbon layer formation on clean metallic beryllium are investigated in situ by X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectroscopy (RBS). The carbon is supplied by an electron beam evaporation device. The deposited films are successively heated to temperatures between 373 and 873 K in steps of 100 K and analysed after each step. After deposition at room temperature an amount of Be2C up to 6×1015 cm−2 is present at the beryllium/carbon interface with elementary carbon on top. A first additional carbide formation takes place after heating to 473 K. For deposited amounts below 5×1016 cm−2 almost all carbon has reacted to carbide after the 673 K step. The carbidisation is complete at 773 K. Applying annealing times between 10 and 30 min characteristic Be2C amounts build up for each temperature. Carbon diffusion into the bulk beryllium does not take place for temperatures below 773 K.