Shubnikov-de Haas and Van der Pauw Hall effect measurements at 1.5 K have been carried out to investigate the existence of a two-dimensional electron gas and to determine subband energies in an Si-delta-doped Al0.27Ga0.73As/GaAs single quantum well. Capacitance-voltage profiling measurements have been performed to characterize the properties of centre delta-doped Al0.27Ga0.73As/GaAs quantum wells. The subband energies, energy wavefunctions and subband carrier densities were determined using the experimental results and a self-consistent calculation taking into account the exchange correlation effects.