Incoherent mesoscopic phenomena in semiconductor structure of macroscopic size

In Si:B MOS-structures (N-B=1.2 x 10(18) cm(-3)), the formation of quasi-2D channel of hopping conductivity occurs in the region, where Fermi energy crosses the impurity band, shifted by gate voltage V-g. Rising gate voltage above zero (V-g > 0, the case of depletion) results in reproducible fluctuations of transverse voltage V-y between Hall probes, at temperatures 4.2-30 K and magnetic fields B up to 1 T, in spite of the macroscopic size of the sample (150 x 50 mu m(2)) and the potential probe ledges (15 x 5 mu m(2)).