In this work, we present recent achievements on the low-temperature (∼ 300 ° C) molecular beam epitaxial growth of high Ge content Si/SiGe modulation-doped multiple quantum well structures on Si0.5Ge0.5 pseudosubstrates. High-resolution X-ray reflectivity and diffraction experiments performed at the Swiss Light Source synchrotron, as well as analysis by transmission electron microscopy, showed very good control of the growth parameters and interface r.m.s. roughness as low as 0.4nm. © 2005 Elsevier B.V. All rights reserved.