Self‐Organized Growth of Quantum Dots and Quantum Wires by Combination of Focused Ion Beams and Molecular Beam Epitaxy

Abstract

The combination of focused ion beam (FIB) implantation and molecular beam epitaxy (MBE) as ultrahigh‐vacuum (UHV) processes allows for nm‐resolution fabrication both in lateral as well as in growth direction. The authors exploit self‐organized growth of Stranski‐Krastanov InxGa1‐x. As quantum dots and III–V nanowire structures, both initiated by FIB‐implantation of different ion species. Samples are transferred between the FIB and the MBE by UHV‐tunnels or a separate UHV‐suitcase which links instruments far away from each other. Since the whole process is within the UHV, no wet or dry chemistry deteriorates the solid‐state interfaces which increases the purity and the reproducibility. Since the available FIB ion species are not only Gallium, but around 40 elements of the periodic table, this method is very versatile and covers even elements which are usually not introduced in a GaAs‐MBE chamber due to purity reasons. Thus, beside site controlled growth any FIB doping, before, in between, due to UHV transfer and after the MBE‐growth becomes possible.