Evaluation of mobility gaps and density of localized hole states in p-Ge/Ge1-xSix heterostructures in the quantum Hall effect mode

The temperature (0.1 K less than or similar to T less than or similar to 20 K) and magnetic field (0 T less than or similar to B less than or similar to 12 T) dependences of the longitudinal (rho(xx)) and Hall (rho(xy)) resistivities have been studied in detail for p-Ge/Ge1 - xSix (x = 0.07) multilayer heterostructures with hole density p = (2.4-2.6) x 10(11) cm(-2) and mobility mu = (1.1-1.7) x 10(4) cm(2) V-1 s(-1). The energy spectrum parameters of two-dimensional (2D) hole gas in the quantum Hall effect mode have been determined. The mobility gap W = (2-2.5) meV and the background density of localized states g(c) = (5-7) x 10(10) cm(-2) meV(-1) for the filling factors nu = 1 and 2. The results are discussed in terms of long-range impurity potential models for selectively doped 2D systems. (C) 2002 MAIK "Nauka / Interperiodica".