Controllable p-n switching behaviors of GaAs nanowires via an interface effect

Due to the extraordinary large surface-to-volume ratio, surface effects on semiconductor nanowires have been extensively investigated in recent years for various technological applications. Here, we present a facile interface trapping approach to alter electronic transport properties of GaAs nanowires as a function of diameter utilizing the acceptor-like defect states located between the intrinsic nanowire and its amorphous native oxide shell. Using a nanowire field-effect transistor (FET) device structure, p- to n-channel switching behaviors have been achieved with increasing NW diameters. Interestingly, this oxide interface is shown to induce a space-charge layer penetrating deep into the thin nanowire to deplete all electrons, leading to inversion and thus p-type conduction as compared to the thick and intrinsically n-type GaAs NWs. More generally, all of these might also be applicable to other nanowire material systems with similar interface trapping effects; therefore, careful device design considerations are required for achieving the optimal nanowire device performances. © 2012 American Chemical Society.