| Photodetector plays an important role in the field of sensors, and it has been widely used in the military and all national economy, such as missile guidance, infrared night vision, optical communication, industrial control, etc. In the military field, the timely and effective communication has become an important part of modern war. Traditional communication methods have the features of easy to be intercepted and their safety is not high. Ultraviolet communication, a new means of communication that is difficult to be detected and intercepted, has high application value in military field. Microelectronic industry based on silicon has met the development bottleneck, and the silicon cost and its complexity of the lithography process have become the two mountains of the development of chip industry. In view of these difficulties, fullerenes, carbon nanotubes,graphene and a series of carbon materials have been found which offer a new way to solve these problems. This thesis will focus on discussing how to use the third generation of semiconductor materials, that is, ZnO with graphene to fabricate the Schottky junction ultraviolet photodetector and the feasibility of full carbon photodetector, and study their photoelectric performance and find the physical meaning behind them. The specific content is as follows:1. Graphene is ideal electrode material because it has outstanding transparent and conductive properties. ZnO is one of the third generation semiconductor materials which has broad and direct bandgap, and it is widely studied because of their excellent properties.However, since the nanostructures of ZnO synthesis process are uncontrollable and complex, it hard to play a real role in the application of photoelectric detection. This thesis will propose a new method of using graphene and ZnO single crystal substrate. On the one hand, it can avoid the complex material synthesis process, on the other hand, it can obtain a good Schottky contact between ZnO, leading to the outstanding performance of this device. The electrical and optical characterizations suggest that this device based on ZnO and Graphene Schottky junction has high responsivity, detectivity and gain as 3 X 104AW-1,4.33×1014 cmHz1/2W-1, and 105 respectively.2. Carbon nanotube has two types as metal and semiconductor type. The metal type of carbon nanotube has the potential application as interconnected materials in microelectronic technology, and the semiconductor type can be used as absorption layer in near-infrared photodetector due to its near-infrared bandgap. But the tubular structure of nanotube is difficult to be contacted with other electrode materials, especially graphene.We put forward the method that using Langmuir-Blodgett process to assemble the carbon nanotubes formed thin film. The experimental results showed that the carbon nanotubes film and graphene have good contact to form Schottky junction. The performance testing shows that the device has ultrafast response speed, i.e., the rise and fall time reached 68 and 78?s respectively. And the spectral response testing shows the excellent characteristics of wide spectral response.Based on the research of the above two projects, it proved that the non-nanostructures of ZnO materials have good photoelectric performance, and the manufacturing process of device is very simple, indicating the practical application of the ultraviolet detection. The arrangement of carbon nanotubes film and graphene formed Schottky junction photodetector has the characteristics of high speed and broadband spectral response. The outstanding performances of this device by using all-carbon materials bring the huge potential for future photoelectric application. |
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