Research Of Lateral Structure Zinc Oxide Nanowire Arrays UV Detector

With the gradual deterioration of the ecological environment and the development of science and technology, people pay more and more attention to health problems, especially on the skin protection and environmental health monitoring, which lead to an increasing need for the UV sensor used in multi-node detecting in internet of things technology, especially for device with high sensitivity and miniaturization. Zinc oxide(Zn O) nanostructures with a high degree of crystallization and large ratio of surface area and volume becomes the preferential choice for such device applications.Through a rigorous and detailed exploration of the basic procedures of IC fabrication, and through a deep investigation of the fundamental physical mechanism, we tried to combine nanotechnology and traditional microelectronic technology together, and on-chip fabricated Zn O nanowire arrays UV detector using the hydrothermal method. On the premise of the integrity of nanowire structures and characteristics and the overall device uniformity, the gain of the device has been significantly improved, and the response and recovery time have been shorten effectively.The main contents and results are as follows:1? The influence of substrate shape on the nanowire growth has been investigated, through an observation of the vertical Zn O nanowire arrays grown on different substrates and with different annealing conditions. Four different procedures for fabricate lateral Zn O arrays has been compared, in order to analysis the pros and cons for each of them and to finally determine the device fabrication procedures. 2? The lateral growth evolution in the procedure of stripping seed layers has been studied, and it is believed that Zn O nanowires are grown on the corner of the electrode steps, which makes the bridging device structure possible.3? We added the post processing procedures, which involved the remove of additional inclined nanowires and reinforce the electrode after the growth of the nanowire arrays. It significantly increased the device performance, and meanwhile verified feasibility of combining the nano fabrication technology into traditional microelectronic processing.4? Two kinds of electrode structures are applied, i.e., Cr and Au. Because Cr electrode will restrain nanowires from growing vertically on top of it, the laterally grown nanowire is long enough to reach the other side of the electrode. The corresponding photoelectric response mechanism is photoconduction controlled by surface oxide ion adsorption. Although the photocurrent is large, the gain is low, and the response speed is slow. A secondary electrode can be fabricated after the growth of the nanowire arrays, which directly contacts with the end of the nanowire to form a Schottky contact. The photoelectric response mechanism then changes to photovoltaic effect, which has greatly improved the gain and response speed. Because Au is catalysis for Zn O nanowire growth, nanowires grown in lateral direction will compete with those grown in vertical direction, and hence the laterally grown nanowires are not long enough to reach the other side of the electrode. Nanowires from two sides of the electrodes will meet with each other and form a bridging junction, however, this will turn the photoconduction mechanism from surface ion controlled into a bridging junction controlled, which yields the best device performance. At room temperature, under UV radiation of 20 m W/cm2 and of 365 nm in wavelength, the dark current is 10-9A with 1V bias voltage, the gain is up to 8×105, the respond time is 1.1s, and the recovery time is 1.3s.