Investigation of GaAs/AlGaAs interfaces by reflectance-difference spectroscopy Xiaoling Ye, Y. H. Chen, Bo Xu, Y. P. Zeng and Z. G. Wang Eur. Phys. J. Appl. Phys., 27 1-3 (2004) 297-300 Published online: 15 July 2004 DOI: 10.1051/epjap:2004080