P-n junctions in planar GaAs nanowires

Control over the doping at the nanoscale during the growth of nanostructures is one of the key challenges of device fabrication. In this work we study p (Zn)- and n (Sn)- doping distributions and a formation of 3D p-n junctions in planar GaAs nanowires grown on doped GaAs substrates. We employ a combination of scanning electron microscopy, transmission electron microscopy, conductive atomic force microscopy studies supported by theoretical analysis and numerical simulations to investigate and explain the nanowire morphology and doping distribution inside. Our studies show that the n-p-n or p-n-p "bipolar transistor"-like lateral nanostructures can be formed during the p-n or n-p growth of planar nanowires on 2 degrees misoriented (001) GaAs substrates. Whereas core-shell "field effect transistor"- like structures can be synthesized on singular (001) substrates. We show that the effect of the substrate misorientation on the 3D doping distribution originates from preferable incorporation of dopants in polar side facets compared to a non-polar top (001) facet.