Fachgruppe Nanostrukturierte Materialien    

We present a method which increases the versatility of molecular beam epitaxy through multiple application of a stationary shadow mask. The method is based on selected area growth in the overlap of the incidence regions of two molecular beams impinging through different apertures of the mask. The width of the overlap depends on the incidence angles of the beams which can be adjusted in situ. Size-control of CdZnSe quantum-well (QW) islands with a precision of 20 nm by varying the distance between the apertures can be obtained. Without Se beam, a minor quantity of Cd is incorporated in the matrix modulating the band-gap energy by just 5 meV. Cathodoluminescence(CL) of nanoscale QW islands shows dot-like behavior, i.e., sharp emission lines that are attributed to different excited states and a blueshift of the CL on reducing the island dimensions.