Research On Deep-uv Detectors Based On Carbot Dots

In recent years,wide-bandgap deep ultraviolet(UV)photodetectors have become a research hotspot because of their demand in many application fields.However,some items are still worth considering including the growth of the material film,the cost and performance of the device,and the heavy metal and gas pollution caused during the preparation process.Based on the above problems,a deep-UV photodetector based on carbon dot materials is designed and its performance is studied.The carbon dot as a carbon-based natural wide bandgap material has superior absorption characteristics in the deep ultraviolet region,and the electrochemical process of using the distilled water as the electrolyte in the preparation process of the carbon dot material is green and natural.The device is easy to prepare and does not require large and complex equipment.The specific research contents of this paper are as follows:Carbon dots are first prepared by electrochemical methods and their properties are studied.,During the process for carbon dots,a pure graphite rod is used as a carbon source for stripping carbon dots,and distilled water is used as an electrolyte,and a DC voltage of 60 V is applied.It is found that the particle size of carbon dots covers 2.3-8 nm and its average size is 3.3 nm.There are two main elements,of carbon and oxygen detected,and hydrophilic hydroxyl functional groups existed on the surface of the carbon dots.carbon dots have strong absorption in the deep ultraviolet region,and the maximum absorption wavelength is at 230 nm.Secondly,i a deep ultraviolet optoelectronic device based on the above carbon dots designed and fabricated,and its performance is estimeated Such kind of photodetector is based on the photoconductive structure of the carbon dot and the metal interdigital electrode pattern.The device has a dark current of about 98.8n A at a bias voltage of 4V,a current of about 18.6?A at a254 nm ultraviolet light,and a light-to-dark current switch ratio of 188.This preliminarily results suggested that carbon dot as a light absorbing material of the device has a certain detection capability in deep ultraviolet.In addition,the device exhibit good stability,and the vacuum environment will greatly reduce the dark current of the device.Finally,several different approaches are explored to improve t the performance of such kind of device including changing the film formation process of the carbon dots,carbon dot concentration and the electrode spacing.The results show that the photocurrent of the device increased by 2.57 times under 254 nm ultraviolet light using carbon dot film by spinning coating with the addition of dispersant PVA solution.carbon dot concentration study shows that among the1.1%?4.4% carbon dots,the device with 2.2% carbon dot concentration is better than those of the other two groups.The photocurrent of the device could reach 375?A.When the electrode pair pitch of the interdigital electrodes in the electrode structure is reduced from 500 ?m to 100 ?m,the optical responsivity of the device is increased up to 3.87mA/W.