AN APPLICATION OF THE STATISTICAL SHIFT MODEL TO THE INVERTED MEYER-NELDEL, M-N, RELATIONSHIP IN HEAVILY-DOPED MICROCRYSTALLINE SI, MU-C-SI

The dark conductivity of heavily-doped mu c-Si films, comprised of dop ed Si crystallites encapsulated in doped a-Si:H, displays an inverted M-N relationship, sigma(0) approximate to C exp (E(0)*/E(0)), between the conductivity prefactor, sigma(0), and the conductivity activatio n energy, E(0), with a negative value for E(0). A positive value of E (0) for a-Si:H films derives from a statistical shift of the Fermi lev el by doping up to, but not deeply into the band-tail density of state s, DOS, whereas a negative value of E(0) means that the Fermi level ha s moved deeply into the band-tail. The negative values of E(0) for hea vily-doped mu c-Si are explained by degenerately doped Si crystallites , and an alignment of the band edges in which the Fermi level is then positioned well within the band-tail of the a-Si:H that surrounds thes e Si crystallites.