n-doped InGaP Nanowire Shells in Core-Shell pn-junctions

We report on the characterization of n-doped InGaP nanowire shells in GaAs/InGaP core-multishell nanowires grown by metal organic vapor phase epitaxy. Multi-tip scanning tunneling microscopy allowed for contact independent resistance profiling of the n-InGaP shells around i-GaAs nanowire cores, resulting in an estimated donor concentration of up to
$\mathrm{N}_{\mathrm{D}}=7\mathrm{x}10^{18}\mathrm{cm}^{-3}$
. Consequently, ohmic Ge/Ni/Ge/Au contacts to these shells are achieved by annealing at
$\mathrm{T}=320^{\circ}\mathrm{C}$
. For the analysis of a p-GaAs/n-InGaP heterojunction, core-shell nanowires are embedded in a height-controlled photoresist layer and selectively wet etched. After contact deposition, current-voltage measurements of the pn-junctions reveal doping dependent diode characteristics with higher leakage currents under reverse bias with increasing doping concentration of the n-InGaP. Successful n-doping of the n-InGaP NW shell is further verified by electroluminescence spectroscopy of p-GaAs/n-InGaP heterojunctions.