Observation of a 2D Electron Gas and the Tuning of the Electrical Conductance of ZnO Nanowires by Controllable Surface Band‐Bending

Abstract Direct experimental evidence for the existence of a 2D electron gas in devices based on ZnO nanowires (NWs) is presented. A two‐channel core/shell model is proposed for the interpretation of the temperature‐dependent current–voltage ( I – V ) characteristics of the ZnO NW, where a mixed metallic–semiconducting behavior is observed. The experimental results are quantitatively analyzed using a weak‐localization theory, and suggest that the NW is composed of a “bulk” semiconducting core with a metallic surface accumulation layer, which is basically a 2D electron gas in which the electron–phonon inelastic scattering is much weaker than the electron–electron inelastic scattering. A series of I – V measurements on a single NW device are carried out by alternating the atmosphere (vacuum, H 2 , vacuum, O 2 ), and a reversible change in the conductance from metallic to semiconducting is achieved, indicating the surface accumulation layer is likely hydroxide‐induced. Such results strongly support the two‐channel model and demonstrate the controllable tuning of the ZnO NW electrical behavior via surface band‐bending.

Перевод пока недоступен