GaAs based nanowires on silicon - growth and quantum confinement phenomena

In this thesis, we investigate the fabrication and characterization of GaAs-based nanowires and their heterostructures with the aim to realize optically highly efficient emitters with one- and zero-dimensional electronic structure. The nanowires are grown by molecular beam epitaxy without an external catalyst on Si(111) covered with a thin SiO2 layer. We first discuss the sensitivity of SiO2 thickness and growth conditions on successful nanowire nucleation. Furthermore, we demonstrate the growth of GaAs nanowires over a large temperature window from 630 °C to 690 °C and study the influence of growth temperature on growth kinetics, nanowire morphology and crystal defects in the nanowires. The remarkable stability of nanowire growth at high temperatures is a direct consequence of the high thermal stability of the predominant (111)B and (110) growth and sidewall facets. In order to allow for high radiative efficiency of GaAs nanowires and enable the realization of advanced photonic devices, we investigate the overgrowth of GaAs nanowires with an AlGaAs-GaAs shell heterostructure. Here, we demonstrate the fabrication of a nanowire laser structure with GaAs quantum wells in the nanowire shell as the laser gain medium.