Abstract
The effect of cesium adsorption on a thermally-cleaned wafer Si(111)7×7 surface was investigated by measuring the changes in the surface conductivity and capacitance in parallel. It is deduced from the results that a p-type region below the surface was formed in the Si wafer regardless of the type of conduction when it was heated up to 1500 K. The p-type region was 68 to 7 µm thick with an acceptor concentration of 1015 to 1016 cm-3 in n-type Si. Electrical conduction was observed in the Cs overlayer with coverages of more than 2.4×1014 atoms·cm-2. The overall dependence of the surface impedance upon the Cs coverage and frequency are well understood qualitatively.