Photoelectric Detectors Constructed By ZnO-based Nano-composites

Silicon (Si) is a representative of the first generation semiconductor materials whose content is very rich in the earth and is just less than that of oxygen. Both its purification and crystallization are much of convenient and low cost. Silicon based semiconductor devices can work at high temperature and have good anti-radiation performance which are particularly suitable for the production of high power devices. Therefore, silicon has become the most widely used semiconductor materials, and so far 99% of the integrated circuits are made from silicon materials. Zinc oxide (ZnO) is a representative of the third generation semiconductor materials, belonging to the II-VI family direct wide band gap compound semiconductors. At room temperature, its band gap is up to 3.37 eV and its exciton binding energy is as high as 60 meV which is much higher than gallium nitride's (GaN) exciton binding energy of 25 meV. Therefore, ZnO has great potential applications in optoelectronic devices such as photoelectronic detectors, light emitting diodes, solar cells, laser diodes and so on. In the field of photoelectronic detection, Si material has good sensitivity under visible light and near infrared light because of its narrow band gap of 1.12 eV. While wide band gap material ZnO has very good detection performance under ultraviolet (UV) light. So, how to combine these two materials well and both of them play out of excellent performance, has been a research hotspot in the field of photoelectric detection. It will lay a solid foundation for their commercial application if the third generation semiconductors and Si material can be well integrated in devices.The work of this doctoral dissertation is around ZnO and its nano-composite materials. We have synthesized ZnO-TeO2 nano-composite material and zinc telluride oxygen composite film through improving the traditional chemical vapor deposition (CVD) method for preparing ZnO nanorods. They were integrated with Si substrate for designing and developing innovative photoelectric detector successfully. The excellent photoelectric detection performance of the devices showed important potential values in scientific research and practical application.To synthesize high quality ZnO nanorods,2D graphene has been introduced between Si substrate and ZnO nanorods. Here, photoelectric detectors based on ZnO nanorods with an Au/ZnO/Graphene/Si/InGa structure have been fabricated. At the same time, comparable device without graphene constructed by an Au/ZnO/Si/InGa structure has also been fabricated. The presence of graphene made ZnO nanorods synthesized by hydrothermal method compact and well crystalline. The detection performance under UV light of the photoelectric detectors with graphene was more excellent than those devices without graphene. In addition, the field emission test of ZnO nanorods showed that the field emission properties of ZnO nanorods grown on Si substrate with graphene were better than those grown directly on bare Si substrates. This work provides important reference for ZnO-based photoelectronic detector integrating with Si substrate.Considering various of nano materials can be synthesized by CVD method, based on the traditional gas phase transport method for preparing ZnO nanorods, tellurium powder was first added into evaporation raw materials and ZnO-TeO2 composite nano-materials were successfully synthesized. Then three groups of detectors with an Au/ZnO-TeO2 composite nano-materials/Si/InGa structure were fabricated. The photoelectric performance tests of all the devices were carried out under the zero bias, which shown good self-driving characteristics. The three devices showed good selective detection performance. The first group detectors had good response to UV light whose wavelength is raged in 290 nm to 380 nm while have no response to visible (VIS) and near infrared (NIR) lights. The second group detectors had obvious response to UV and NIR lights whose wavelengths were raged in 300 nm to 380 nm and 1000 nm to 1100 nm respectively while have no response to VIS light. The third group detectors had good selective detection to NIR whose center wavelength was around 1040 nm while they nearly had no response to UV and VTS lights. In a word, self-driving photoelectric detectors which had selectivity to detect UV and NIR lights were first manufactured through regulating each composition's relative content of ZnO-TeO2 composite nanorods. This work showed important potential research and application values.On the basis of previous literature research and experimental research, a zinc tellurium oxygen (ZTO) compound thin film material was synthesized using the preparation method of ZnO-TeO2 composite nanorods. It contained ZnTe and TeO2 two ingredients by XRD and XPS analysis. It is well-known that ZnTe-based photodetectors have excellent photoelectric response to VIS light, so a broad band photoelectric detector constructed by the structure of Au/ZTO compound film/Si/InGa has been fabricated successfully. The detector showed good detectation to UV, VIS and NIR lights under zero-bias. Compared with ZnO-TeO2 composite nanorod detectors, ZTO compound film detector made up for the VIS detectation, and its detection performance had been greatly improved when detecting UV and NIR lights.