Modeling And Design Of Composite Photodetector For UV Spectral Range

With the development of civil and military industries, the research of ultraviolet detection technology has been in hot pursuit by the academic and industrial circles. The expansion of market demand makes operating environment of the ultraviolet detector more complex and demanding. Therefore, high wavelength selectivity, wide detection range, high temperature stability, simple process and low cost has become the development direction of the UV detector with the market orientation. The ultraviolet detection system based on standard CMOS technology can overcome many shortcomings in the present market. At present, meeting the requirements of wavelength selective and low light level detection requirements of the UV detector design is the main bottleneck single chip integrated silicon based UV detection system.This thesis aims to present a design scheme for UV photodetector, and verify its feasibility from two aspects of theory and test. It put the research idea and the framework of the article based on photosensitive physical principle of semiconductor, and combining with the characteristics of CMOS technology and existing research foundations. By researched on the principle of three basic optical devices, a geometry of the device with high sensitivity and a design scheme of CMOS-based photodetector was proposed. It ideally demonstrated how to utilize the advantaged, and how to avoid the disadvantageous for the fundamental photosensitive devices. And by establishing three analytic models of the static model based on charge controlled, Pwell/Nwell junction/PMOSFET model, and P+-Nwell-Pwell voltage-controlled model, to verify the feasibility of the device in theory. In addition, this approach makes it easier to get the specific information for optimizing the design of composite device. Then, analyzes the characteristics of threshold(with or without illuminated),the I-V characteristics and spectral characteristics of the device from the perspective of theory. The model has been simulated by MATLAB and spectral response for the device is discussed. Process influences on the spectral response as well as the spectral response, DC response and minimum detectable optical power of the device are studied in this paper.The proposed composite device was duplicated and concatenated to form each30×30 array with a total area of 378 ?m × 378 ?m and was manufactured using GSMC0.18? m CMOS technology. 79.3% of our structure area is Nwell/Pwell photodides and all of these are actually sensitive to UV. At present, we have completed the part of the chiptesting. The DC responsivity decreases rapidly if the intensity of incident optical power were greater than 10 ?W. Its responsivity enhanced much in contrast with a traditional silicon-based UV photodiode. The test results reveal that the presented photodetector,which just like predicted by the model, is an effective way to solve the low response of silicon-based UV detector. In a word, the presented photodetector has a big potential application value in weak light and UV/blue light detection.