InAs/GaAs self-assembled quantum dots (QDs) grown by molecular beam epitaxy are showing considerable promise for the development of GaAs-based optoelectronic devices for application in the 1300-1550 nm range [1-4]. However the growth of these structures is complex since many parameters influence the emission properties of the structures. In this talk I will review our recent progress in controlling the growth and properties of multilayer QD structures in which the individual QD layers are separated by a spacer layer of well-defined thickness [4-6]. In particular I will show how the spacer layer thickness, strain relaxation and control of the In/Ga intermixing process all play a crucial role in extending the emission to long wavelengths. Scanning tunnelling microscopy (STM), atomic force microscopy (AFM) and transmission electron microscopy (TEM) have all be used to provide quantitative information regarding the QD characteristics (density, size and uniformity) and results will be presented for structures that demonstrate emission up to 1500 nm . Finally I will show how the choice of capping material also plays a strong role in determining the emission properties of the QDs and promising results will be presented for both InGaAs and GaInNAs capping layers.
 P.B. Joyce, T.J. Krzyzewski, G.R. Bell, T.S. Jones, S. Malik, D. Childs, R. Murray, Phys. Rev. B 62 (2000) 10891
 P.B. Joyce, T.J. Krzyzewski, G.R. Bell, T.S. Jones, E.C. Le Ru, R. Murray, Phys. Rev. B 64 (2001) 235317.
 E.C. Le Ru, U. Marchioni, A. Bennett, P.B. Joyce, T.S. Jones, R. Murray; Mat. Sci. and Engineering B 88 (2002) 164.
 E.C. Le Ru, P. Howe, R. Murray, T.S. Jones, Phys. Rev. B 67 (2003) 16530.
 P.B. Joyce, T.J. Krzyzewski, P.H. Steans, G.R. Bell, J.H. Neave, T.S. Jones, J. Cryst. Growth 244 (2002) 39.
 P.B. Joyce, E.C. Le Ru, T.J. Krzyzewski, G.R. Bell, R. Murray, T.S. Jones, Phys. Rev. B 66 (2002) 75316.