An ultra-high-vacuum system for computer-integrated measurements of the Hall effect and conductivity of two-dimensional films

The design of an ultra-high-vacuum system, which is equipped with a special unit for Hall measurements at low temperatures (120-293 K), an evaporation unit with shields cooled by liquid nitrogen, and a low-energy electron dif fraction analyzer, is described. The unit for Hall measurements is based on a nitrogen-cooled coil, into which a six-probe head is built at a depth of 15 mm. The head is intended for measuring Hall parameters of ordered two-d imensional films on silicon single crystals. A version of the two-frequency method with double synchronous detection is implemented in a computer-cont rolled automated system for Hall voltage and conductivity measurements. The system has a unit for compensating nonequipotential voltages, thus allowin g for Hall voltage measurements with an rms error of below 1.5%. The mobili ties of carriers and their concentrations in atomically clean silicon subst rates and surface chromium phases on silicon were measured.