Effects of bias stress on ZnO nanowire field-effect transistors fabricated with organic gate nanodielectrics

Sanghyun Ju, School of Electrical and Computer Engineering, Institute for Nanoelectronics and Computing, Birck Nanotechnology Center, Purdue University
David B. Janes, School of Electrical and Computer Engineering, The Institute for Nanoelectronics and Computing,
Gang Lu, Department of Chemistry and The Materials Research Center, and The Institute for Nanoelectronics
Antonio Facchetti, Department of Chemistry and The Materials Research Center, and The Institute for Nanoelectronics
Tobin J. Marks, Department of Chemistry and The Materials Research Center, and The Institute for Nanoelectronics

Date of this Version

November 2006

Citation

DOI: 10.1063/1.2378445

This document has been peer-reviewed.

 

Abstract

The effects of bias stress gate stress or drain stress on nanowire field-effect transistor NW-FET stability were investigated as a function of stress bias and stress time. The n-channel NW-FETs used a nanoscopic self-assembled organic gate insulator, and each device contained a single ZnO nanowire. Before stress, the off current is limited by a leakage current in the 1 nA range, which increases as the gate to source bias becomes increasingly negative. The devices also exhibited significant changes in threshold voltage Vth and off current over 500 repeated measurement sweeps. The leakage current was significantly reduced after gate stress, but not after drain stress. Vth variations observed upon successive bias sweeps for devices following gate stress or drain stress were smaller than the Vth variation of unstressed devices. These observations suggest that gate stress and drain stress modify the ZnO nanowire-gate insulator interface, which can reduce electron trapping at the surface and therefore reduce the off current levels and variations in Vth. These results confirm that gate and drain stresses are effective means to stabilize device operation and provide high performance transistors with impressive reliabilities.

 

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