Charge state of potassium on metal and semiconductor surfaces studied by low-energyD+scattering

On the basis of the neutralization of low-energy (${\mathit{E}}_0$=50 eV) ${\mathrm{D}}^{+}$ ions, the nature of bonding of potassium on metal and semiconductor surfaces has been studied in a low-coverage region (Θ<0.2). It is concluded that the K adatoms on the Si(100) surface are highly ionic while those on the Pt(111) and W(110) surfaces are characterized by covalent or metallic bonding. The ionic nature of potassium can be ascribed to the existence of the empty dangling-bond states and/or the bulk band gap of the semiconductor substrate.