We have calculated the disorder broadening of the Landau-level subbands of a two-dimensional electron gas in a periodic modulation potential using the self-consistent Born approximation (SCBA). Systems with the same disorder broadening of the Landau levels in the absence of modulation are compared. We find that the subband structure of the Landau level that results from adding a potential modulation is obscured much less effectively in rough disorder potentials than in smooth disorder potentials. We work in the strong-magnetic-field limit and exploit the absence of Landau-level mixing to greatly simplify the calculation. The accuracy of the SCBA in the limit of smooth disorder potentials is assessed by comparing with densities of states evaluated from inhomogeneous line broadening.

• Received 10 November 1992

DOI:https://doi.org/10.1103/PhysRevB.47.6566