Electronic transport in p-type doped GaAs nanowires

It is shown that Mg can be used as a p-type nontoxic and noncarcinogenic alternative dopant in GaAs nanowires. The analysis of the temperature dependence of the electrical properties of individual nanowires shows that the electronic transport changes from conduction of free holes, above room temperature, to hopping conduction at lower temperatures. Two hopping conduction mechanisms were observed starting from Mott-VRH and transiting to ES-VRH as temperature drops. The analysis of the hopping conduction allows extracting the values of electrical transport parameters in the NWs. The average doping levels were found to change from nanowire to nanowire. This anomaly was explained in terms of variations of growth rate from wire to wire due to the characteristic growth mechanism of free-standing nanowires, as well as due to the polytypism in the NWs.