THE LANDAU-LEVEL DENSITY OF STATES AS A FUNCTION OF FERMI ENERGY IN THE 2-DIMENSIONAL ELECTRON-GAS

We have made quantitative determinations of the density of states (DOS ) of Landau levels in a 2d system whose density can be varied using a gate bias. A novel technique employs two normalization conditions to e xtract the DOS as a function of Fermi energy in the 2d electron gas fr om capacitance data. No knowledge of sample parameters is required exc ept for the sample area. In contrast with previous results, we find th at Lorentzian lineshapes give excellent fits to the Landau level struc ture without need for added background and with linewidths that are in dependent of magnetic field strength.