Field electron emission study of Ti and Hf adsorption layers on W

Adsorption, nucleation, and crystal growth of hafnium and titanium deposited from vapor in ultra-high vacuum onto thermally cleaned tungsten emitters have been studied by ®eld electron emission microscopy methods. The Ti adsorption on W surface was typical of metals of low intersolubility. The local work function decreases monotonically under Ti adsorption and saturates. Local work function values at saturation were equal to 3.0 eV on the (0 1 6)W face, 3.5 eV on the (0 1 1)W and (1 1 1)W faces, 3.75 eVon the (0 0 1)W face, and 3.95 eVon the (1 1 2)W face. The Hf interaction with W was much stronger and much more anisotropic than the Ti±W interaction. The formation of an intermetallic compound between Hf and W caused strong decrease of the local work function on the {0 0 1}W faces, resulting in an unusually high electron emission from these areas. # 2001 Elsevier Science B.V. All rights reserved