Effects of surface passivation on top-down ZnO nanowire transistors

• Unpassivated and passivated ZnO nanowire transistor characteristics are compared.
• These are fabricated using conventional top-down methods.
• Remote plasma atomic layer deposition and anisotropic ICP etch methods are used.
• Unpassivated NWFET show VTH of 6.5 V, on/off ratio of 106 and μo of 31.4 cm2/V s.
• Passivated NWFET show VTH of −10 V, on/off ratio of 104 and μo of 35.5 cm2/V s.

We fabricated unpassivated and passivated zinc oxide (ZnO) nanowire field effect transistors (NWFETs) using conventional top-down method of remote plasma atomic layer deposition and anisotropic dry etch. This paper investigates the effect of Al2O3 passivation on the electrical characteristics of the ZnO NWFETs. Measured unpassivated ZnO NWFETs show a threshold voltage of 6.5 V, drain current on/off ratio of 106 and field effect mobility of 31.4 cm2/V s. Passivated ZnO NWFETs demonstrate threshold voltage shift to −10 V, drain current on/off ratio of 104 and improvement of mobility of 35.5 cm2/V s. The passivated device results indicate suitability for biosensing applications.

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