P -type doping of GaAs nanowires

Abstract

Gallium arsenide (GaAs) nanowires with diameters of 150nm have been grown via metal-organic vapor deposition and were subsequently implanted with Zn64 ions. The amorphized nanowires were annealed at 800°C under arsenic overpressure resulting into a full recrystallization of the nanowires as well as an activation of the implanted acceptors. Consequently, we observe a strong increase in conductivity of the GaAs:Zn nanowires, where a simple estimation of the activated acceptors matches the implantation concentration.

Local Electrical Analysis of a Single Semiconductor Nanowire by Kelvin Probe Force Microscopy

“…This leads to a lower and a more inhomogeneous doping concentration in the nanowire than intended. Considering this fact and the fact that not all acceptors are ionized at room temperature [6] the value extracted from the measurement is in reasonably good agreement with the expected carrier concentration.…”

“…V S is the surface potential and the hole mobility can be calculated by µ h =µ 0 /[1+(N A /10 18 cm -3 ) 1/2 ]. With typical values for p-GaAs of µ 0 =450 cm 2 /Vs, V S =0.45 V, ε r =13.1 [6] and an average radius of r 0 =120 nm, an effective carrier concentration of p ~ 6·10 17 cm -3 can be estimated.…”

“…The nanowires were grown along the <111> direction on a GaAs <100> substrate, thus resulting in an angle of about 35° with respect to the surface. Subsequently, the nanowires were doped with Zn by ion implantation at room temperature [6]. For the implantation, multiple ion energies were used to reach a homogeneous doping profile.…”

Near-thermal limit gating in heavily doped III-V semiconductor nanowires using polymer electrolytes

“…Unfortunately, it is not clear how to achieve nanowire shell growth with controlled axial doping variation. Ion implantation is an alternative but one that causes significant damage to the nanowire [28]. Thus for our p-GaAs nanowire MOSFETs we are trapped in an unfortunate trade-off between contact resistance and gate performance governed by shell doping density.…”

“…This makes the Schottky barrier depletion region very narrow, raising the electron tunnelling probability and giving a linear I-V characteristic for the contact. This can be assisted by doping the semiconductor local to the contact by other means, e.g., by ion-implantation [28], or during growth [25,29].…”