Temperature dependence of the Fermi level in the two-zone hybrid model of doped semiconductors

On the basis of the two-zone hybrid model of doped semiconductors suggested earlier (see Phys. Status Solidi (b), vol.156, p.487 (1989)) have analysed the behaviour of the Fermi level and the degree of ionisation of the impurity band over a wide temperature range. The calculation of the density of states is performed using a modified Matsubara-Toyozawa method (1960) in which the so-called multiple occupancy corrections are fully taken into account. The results obtained are compared with the corresponding ones of a simpler delta model which is a good approximation of the well known Kane and Morgan density of states relations.