Sputtering of beryllium, tungsten, tungsten oxide and mixed W-C layers by deuterium ions in the near-threshold energy range

An experimental method of determination of sputtering yield for current-con ducting materials under ion bombardment of light gases in the near-threshol d energy range has been developed. Such an information is very important in both the purely scientific and applied aspects. This method is based on th e use of special regimes of field ion microscopic analysis. The procedure o f measuring the sputtering yield includes cleaning of the surface in situ b y desorption and evaporation of atoms by the field in order to make atomic- clean and atomic-smooth surface. This method permits to observe single vaca ncies in the irradiated surface, i.e., directly to count the single sputter ed atoms. It has been used for beryllium, technically pure tungsten, tungst en oxide and mixed W-C layer on the tungsten irradiated by deuterium ions. The energy dependence of sputtering yield of those materials by deuterium i ons at energies ranging from 10 to 500 eV is investigated. Experimental res ults for beryllium are in a satisfactory agreement with the calculations of Eckstein st al. Substantial connection between threshold energy of the spu ttering and condition of oxidized surface of tungsten has been ascertained. The threshold energy for sputtering of oxidized tungsten surface is equal to 65 eV. The threshold energy for sputtering of mixed W-C layer has almost the same value as for the pure W. (C) 1999 Elsevier Science B.V. All right s reserved.