Shell-doping of GaAs nanowires with Si for n-type conductivity
GaAs, nanowires, core–shell, Si doping, molecular beam epitaxy, Raman spectroscopy
ABSTRACT We demonstrate the potential of using Si as n-type dopant in GaAs nanowires grown by molecular beam epitaxy. The amphoteric behavior of Si that typically accompanies the vapor–liquid–solid growth mode is adequately controlled when a shell doping scheme is utilized instead, i.e. when a Si-doped GaAs shell layer is grown conformally around the undoped GaAs nanowire core in the vapor–solid mode. The incorporation site of Si was evaluated by Raman spectroscopy, and correlated with the growth conditions of the doped shell. In that way, we identified a growth window that ensures the incorporation of Si as donor, and obtained donor concentrations up to 1 × 1019 cm–3, with the compensation level by Si acceptors remaining below 10%. Finally, resistivity measurements on planarized shell-doped nanowire ensembles were employed to probe the doping efficiency and the surface depletion of free-carriers. The achievement of n-type conductivity for nanowires is essential for the realization of functional devices, and is particularly significant when a dopant as well understood and advantageous as Si is employed.
Tsinghua University Press
Emmanouil Dimakis,Manfred Ramsteiner,Abbes Tahraoui,Henning Riechert,Lutz Geelhaar, Shell-doping of GaAs nanowires with Si for n-type conductivity. NanoRes.2012, 5(11): 796–804