| Silicon based photodetectors have the advantages of stable performance,low dark current,high response and low price.They are widely used in photoelectric detection and other fields,but the detection ability of silicon-based detectors in deep ultraviolet band is limited.Based on the excellent optical properties of Mn doped quantum dots,a condensing structure is proposed to improve the detection sensitivity of silicon-based diodes in UV band.Using the fluorescence characteristics of Zn Cd S: Mn / Zn S quantum dots,the absorbed ultraviolet light can be converted into visible light.Combined with the use of short wave pass cut-off color filter film,the detection ability of silicon-based detector in ultraviolet band is enhanced.Firstly,a Mn doped core-shell structure with high quantum yield was prepared.By increasing the doping ratio of Mn ions in the core layer and increasing the transition probability of defect ions,the quantum yield is improved.Secondly,in order to improve the stability of quantum dots,the preparation method of thick shell quantum dots is optimized,and the high-quality coating of six Zn S shells comes true.The quantum yield can reach 56%.Next,we simulate the light energy utilization of directly coating quantum dots film on silicon-based detector and using condensing structure.It is found that the energy utilization of the former is only 50%.The light energy utilization rate using the concentrating structure can reach more than 90%.Then,the preparation of the concentrating structure is realized.Through actual measurement,the external quantum efficiency of the silicon-based detector with the concentrating structure in the ultraviolet part(260 nm-400 nm)is more than 20%.A highsensitivity ultraviolet detector based on doped quantum dots becomes reality.In addition,quantum dots are also prepared into thin films and used in single channel UVvis spectrum UV imaging system to improve the intensity of UV signal. |
