Characterization of ultrathin InAs quantum wells by TEM-cathodoluminescence and TEM techniques

Emission from ultrathin quantum wells of different thicknesses is studied. In particular, for structures with doped substrate the unintentional deposition of Cu droplets is used as a probe of electron diffusion inside the material. A large diffusion length (L = 8 +/- 3 mum) is found in spite of the presence of quantum dots. In particular, the contribution to the diffusion from re-emission of electrons from quantum dots is evaluated.