Zinc Oxide Nanowire Field Effect Research Articles

Zinc Oxide Nanowire Field Effect Transistor Used as a pH Sensor

An ion sensitive field effect transistor can outperform conventional ion-selective electrodes. Thus, a zinc oxide (ZnO) nanowire field effect transistor (NWFET) pH sensor was fabricated and measured. The sensor contained a channel with 1.7×1018 cm-3 donor concentration and 100 ZnO nanowires in parallel, each with the following dimensions: 10 μm×120 nm×20 nm. The active channel is passivated with an 18 nm Al2O3 layer. The device was measured under a controlled environment with and without pH solutions. The pH range was 3–9 with a sensitivity of 2.48 mV to 10.3 mV. The voltage sensitivity translates to a percentage value of 15%. The measurements obtained before and after the pH solution treatment demonstrate the possibility of re-use of the device by rinsing and brushing the sensing layer.

Simulation study of ZnO nanowire FET arrays for photosensitivity enhancement of UV photodetectors

An ultraviolet photodetector based on zinc oxide nanowire field effect transistor is designed and simulated in three configurations including single nanowire, three parallel and array of six nanowires. Transient response of photodetectors is studied by mixed-mode simulation. Results demonstrate that the light/dark current ratio is increased to 10 for the parallel and array of six nanowires. Transmission percentage of undesired wavelengths increases to 80% in the array of six nanowires, additionally. Furthermore, parallel nanowires detectors enhance photosensitivity from 3.325 in single nanowire structure to 12.477 in parallel structure; however, it does not impact on quantum efficiency. On the other hand, the array of six nanowires structure raises external quantum efficiency substantially from 50% for single nanowire to 58%. Moreover, array structure stables the photodetector in a variety of illumination angles. Although, field effect transistor photodetector structure improves the performance of UV detector and boost photodetector response time, three parallel and array of six nanowires structures slightly increase response time to 8.4 and 9.9 μs, respectively in comparison with single nanowire structure. The proposed UV detector receives an encouraging response to μW range of power light intensity.

Ink-jet printed ZnO nanowire field effect transistors

Semiconducting nanowires provide routes for realizing high-performance electronic devices, but for many applications of such devices low-cost manufacturing techniques are needed. The authors demonstrate here top-gated zinc oxide nanowire field effect transistors (NW-FETs) fabricated by ink-jet printing. High resolution submicrometer gold gaps between source and drain electrodes were defined by a self-aligned ink-jet printing technique, and the nanowires were deposited from solution onto these electrode arrays and gated from the top using a spin-coated poly(methyl methacrylate) gate dielectric. The typical NW-FETs exhibited a mobility of 2–4cm2∕Vs, a current on/off ratio of 104, and a transconductance of 20.5nS. The process provides a pathway for fabrication of NW-FETs by low-cost, large-area solution processing and direct printing techniques.