Low-temperature electron transport in Si with an MBE-grown Sb δ layer

Studies of the electrical properties of Si single crystals with {δ}(Sb) layers of various sheet densities ND, of Sb atoms (5×10¹²--3×10¹⁴cm^-2) have furnished detailed information about the low-temperature features of the electron transport in this system. The metal-type conductivity of {δ} layers at ND>~3×10¹³cm^-2 exhibits manifestations of the weak localization of electrons and electron-electron interaction in a two-dimensional system. The temperature dependence of electron phase relaxation time, the spin-orbit interaction time, and parameter λD of the electron-electron interaction are determined. It is found that a decrease in the electron density in the {δ} layer is accompanied by decrease in the parameter λD. The effect of electron heating by an electric field is used to find the temperature dependence of the electron-phonon relaxation time. At low temperature the hopping-type conductivity of {δ} layers at ND<~1×10¹³cm^-2 is realized; at sufficiently low temperatures (10 K) the two-dimensional Mott law of variable-range hopping is seen. The nonlinearity of the current-voltage characteristics observed is well described by the theory of non-Ohmic hopping conductivity in moderately strong electric fields.