Novel growth and properties of GaAs nanowires on Si substrates

Abstract

Straight, vertically aligned GaAs nanowires were grown on Si(111)substrates coated with thin GaAs buffer layers. We find that theV/III precursor ratio and growth temperature are crucial factors influencing the morphology andquality of buffer layers. A double layer structure, consisting of a thin initial layer grown at lowV/III ratio and low temperature followed by a layer grown at highV/III ratio and high temperature, is crucial for achieving straight, vertically aligned GaAsnanowires on Si(111) substrates. An in situ annealing step at high temperature after bufferlayer growth improves the surface and structural properties of the buffer layer, whichfurther improves the morphology of the GaAs nanowire growth. Through suchoptimizations we show that vertically aligned GaAs nanowires can be fabricated on Si(111)substrates and achieve the same structural and optical properties as GaAs nanowires growndirectly on GaAs(111)B substrates.