Ba. Aronzon et al., OBSERVATION OF CORRELATION GAP IN QUASI-2D IMPURITY BAND OF SI-B MOS STRUCTURE, Czechoslovak journal of Physics, 46, 1996, pp. 2529-2530
We studied longitudinal conductivity sigma of Si:B (N-B approximate to
10(18)cm(-3)) MOS-structures with doped layer thickness 0.5 mu, scann
ing Fermi energy through valence and impurity bands with gate voltage
V-g. The quasi-2D channel, responsible for conductivity in such struct
ures, is formed in the region where the Fermi level crosses the impuri
ty band, shifted by V-g. We have observed two minima in the sigma(V-g)
dependence. The first one, which is due to the gap between extended a
nd localized impurity states, is observed in the temperature range stu
died (4.2-30K), while the second one - only at low enough temperatures
(<6K) and assumed to be associated with correlation effects, leading
to selfconsistent redistribution of electron density.