Electrostatically Gated Graphene-Zinc Oxide Nanowire Heterojunction

Area of Science:

• Materials Science
• Nanotechnology
• Condensed Matter Physics

Background:

• Graphene-based heterojunctions are promising for electronic devices.
• Zinc oxide (ZnO) nanowires offer unique electronic and optical properties.
• Controlling interfacial properties is key to device performance.

Purpose of the Study:

• To present the first electrostatically gated graphene-ZnO nanowire heterojunction for device applications.
• To investigate the effect of oxygen on the electrical characteristics of the graphene-ZnO NW heterojunction.
• To demonstrate gate voltage control over the junction's current.

Main Methods:

• Fabrication of a heterojunction using a sub-nanometer graphene layer and electrochemically grown ZnO nanowires.
• Characterization of current-voltage (I-V) properties under varying conditions (e.g., oxygen environment, back-gate voltage).
• Analysis of electron tunneling through the narrow energy barrier.

Main Results:

• A near-ohmic I-V curve was observed for the pristine graphene-ZnO NW heterojunction.
• Exposure to oxygen shifted the I-V curve to an asymmetric Schottky contact behavior.
• A large current modulation (on/off ratio of 10^3) was achieved by adjusting the back-gate voltage.

Conclusions:

• The graphene-ZnO NW heterojunction exhibits tunable electronic properties based on oxygen interaction and gate voltage.
• Oxygen adsorption on ZnO NWs creates a depletion region, increasing the energy barrier and leading to Schottky behavior.
• Electrostatically gating provides effective control over the junction's current, highlighting its potential for electronic device applications.