In situ Hall measurements of macroscopic electrical properties of chromium-covered Si(111) surfaces

The first in situ Hall measurements of the ordered chromium surface phases on Si(111) substrate and CrSi(111) epitaxial films after their formation ar e presented. Formation of Si(111)-(1 x 1)-Cr (0.1 nm Cr) and Si(111)-[(root 3 x root 3)/30 degrees]-Cr (0.3 nm Cr) surface phases results in an increa se in the sheet resistivity of Si(111)-Cr surface phase samples. The conduc tivities along the surface phases at these chromium thicknesses are very lo w. The conductivity decrease is caused by a decrease in the electron mobili ty in the surface phase layers. Formation of an epitaxial CrSi(111) layer w ith averaged Hall parameters (hole mobility of 440 cm(2).V-1.s(-1), sheet r esistivity of 2.2 . 10(4) Ohm(-1) and sheet hole concentration of 0.65 . 10 (12) cm(-2)) has been observed at 1.5-1.8 nm of chromium thickness.