A semiclassical model with randomly distributed N donor and K x N acceptor
sites and with infinite-range Coulomb interaction is investigated by means
of computer simulations on two-dimensional samples of different sizes. The
shape of the Coulomb correlation gap in the density of one-electron excitat
ions g(epsilon) is obtained for different values of K within a wide energy
interval around the Fermi energy mu. Using simple scaling arguments we demo
nstrate that the true behavior of g(epsilon) in the immediate neighborhood
of mu is hidden by the finite-size effects and find that g(epsilon) further
away from mu is described by a power-law with an exponent, depending on K
and the sign of epsilon - mu. (C) 2001 Published by Elsevier Science B.V.