ABSTRACT
From electron energy loss spectroscopy (EELS) linescans and spectrum images, concentration profiles and maps of vertical quantum well (VQW) are obtained, and a subsequent bandstructure calculation shows up to three confined sublevels in the VQW. When AlxGa1-x As layers are grown on V-grooved GaAs substrates by metal organic chemical vapour deposition, a Ga (gallium) rich VQW appears in the V-groove centre. The width and Ga enrichment of this structure depend on the nominal aluminium concentration and growth temperature. Developed an EELS technique to visualize the VQW using spectrum images. Both techniques, EELS and cathodoluminescence (CL) were employed to understand carrier localization and diffusion in these interconnected V-groove quantum structures. EELS was used to obtain the chemical profile across the VQW. A typical profile contains some 100 spectra, and with acquisition times of 1.5s/spectrnm, drift between adjacent spectra or while scanning through interfaces can be neglected.
