Intra - and inter - layer hopping transport and themetal { non - metal transition in the two - andthree - dimensional systems of - doped semiconductorsP

A percolation theory approach is taken to investigate electron hopping transport and the metal{non-metal transition in n-type-doped semiconductor systems. The activation energy is calculated for inter-layer hopping events in multiple-layer systems. The corresponding critical sheet density for the metal{non-metal transition is calculated, and it is shown that this increases for increasing-layer separation. Consideration of a single-layer has allowed the determination of the activation energy as a function of the sheet density of donors, for intra-layer hopping. The critical concentration c of donors for the metal{non-metal transition in this truly two-dimensional system has been found to be 3:4 10 10 cm ?2 in a GaAs host. Furthermore, by considering a range of host semiconductor crystals, the concentration induced metal{non-metal transition in a two-dimensional distribution of donors of Bohr radius is shown to be given by p c 0:19.