Current-voltage and Optoelectronic Properties of Semiconducting ZnO Nanobelts

We report on electrophoretic alignment of ZnO nanobelt bunches and their electrical and optical properties. The nanobelts were trapped onto a pair of electrodes by using alternating electrical current at frequency between 5 ~ 50 MHz and peak-to-peak amplitude from 2 to 20 V. Their electrical transport properties associated with the photoelectricity were studied at room temperature in the air ambient by using a xenon arc lamp source. Three typical IV characteristics were observed: asymmetry, symmetry and infinite impedance. The photoconductivity measurements show that the photocurrent through ZnO nanobelts increases as about 1.6 power of light intensity. The electron concentration Delta n is estimated to be 3.3times10⁷ cm^-1 at a bias voltage of -3V. Photocurrent decay was also studied through the experiment of photoresponse to illumination, and the decay time was estimated to be about 3 s. Collectively, ZnO nanobelts are demonstrated to be a remarkable optoelectronic material that holds wide applications for nanoscale photonic devices.