A 2D electron gas (2DEG) with a controlled density of repulsive scatters at the interface is obtained by irradiation of AlGaAs/GaAs heterojunctions with 1 MeV electrons. Measurements of the magnetotransport yield that the plateaus in the Hall resistance are at their quantized values Rxy = h/e2v (v is the integer filling factor) but show a significant broadening. The lineposition of the cyclotron resonance is found to be shifted to higher energies such that Full-size image with the energy before irradiation and . From the investigation on partially up to fully annealed samples we found that is proportional to nsc the density of scatters of the SDEG.