Subband structure and band bending in symmetric modulation-doped double quantum wells F. Ungan, E. Ozturk, Y. Ergun and I. Sokmen Eur. Phys. J. Appl. Phys., 29 1 (2005) 27-31 Published online: 21 December 2004 DOI: 10.1051/epjap:2004209