An electric-field assisted growth control methodology for integrating ZnO nanorods with microstructures

Abstract

The growth control of ZnO nanorods bridging over two microelectrodes in a three-electrode structure (the top cathode and anode, and the bottom gate) was realized using a wet chemical method with the assistance of an electric field generated by applying AC sine wave power on the top electrodes and a DC voltage on the bottom gate. A numerical control model for controlling the growth position, direction and density of ZnO nanorods on the microstructure was established based on the simulation of the electric-field distribution around the microstructures. The three input parameters in the numerical control model were defined as the peak-to-peak voltage of the AC sine wave (x1), the frequency of the AC sine wave (x2) and gate voltage (x3). Moreover, five output parameters (y1, y2, y3, y4, y5) in the model were defined as the electric field intensities at specific points on the electrodes to characterize the growth rate, direction, position and morphology of the ZnO nanorods integrated with the microelectrodes. The relationship between the defined outputs and inputs were established using 3(rd) polynomial fitting, which served as the numerical control model for the prediction of nanorod growth. The experimental results validated that growth control methodology provides us with an effective approach to integrate ZnO nanorods into devices.

Zinc oxide nanorod field effect transistor for long-time cellular force measurement

“…The EDX results of ZnO nanorods prove the atomic ratio of zinc to oxygen is near the stoichiometric composition (1:1). TEM images of ZnO nanorods, SAED pattern and HRTEM examination indicate the single crystal structure of ZnO nanorods and their <0001> growth direction22.…”

“…Afterwards, ZnO nanorods are synthesized site-selectively at the opposite ends of the Au source and drain electrodes, and cross connected between two electrodes by using an electric-field assisted wet chemical method (Fig. 1c)22. The growth of ZnO nanorods can be controlled by applying certain electric field on the microchip.…”

“…The growth of ZnO nanorods can be controlled by applying certain electric field on the microchip and detailed discussions can be found in our previous paper22. The fabricated ZnO nanorods is about 1~2 μm in length and about 300~500 nm in diameter.…”

“…TEM images of ZnO nanorods, SAED pattern and HRTEM examination indicate the single crystal structure of ZnO nanorods and their <0001> growth direction. The structural properties of ZnO nanorods are characterized using SEM (JSM-6460LV)22.…”

“…Here, a ZnO nanorod field effect transistor (FET) is proposed. ZnO nanorods are synthesized at the opposite ends of two micro electrodes and cross connected between the electrodes by using an electric-field assisted hydrothermal growth method22 to form a FET. Forces exerted by cells onto underlying ZnO nanorods are transduced into Schottky barrier change at semiconductor/metal interface for piezoelectricity of ZnO, which is detected by using a frequency mixing effect of semiconducting nanorods and a lock-in amplifier.…”