Wet Chemical Synthesis And Photoelectric Properties Of Chalcogenide (Cadmium,Bismuth,Manganese) Quantum Dots

Cadmium sulfide quantum dots(CdS QDs),strontium sulfide quantum dots(Bi2S3 QDs)and manganese sulfide quantum dots(MnS QDs)are very important transition metal sulfide semiconductor materials with excellent optical and electrical properties,and they have wide range of research and application in biosensors,photocatalysis,solar cells,light-emitting diodes,photodetectors and other fields.At the same time,because of the small size of CdS QDs,Bi2S3 QDs and MnS QDs,they have strong absorption for ultraviolet light,and their application in ultraviolet photodetectors has become one of the c urrent research hotspots.Therefore,CdS QDs.Bi2S3 QDs and MnS QDs are synthesized in this thesis,and the ultraviblet detectors are prepared using the three QDs.In this work,the materials and devices were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),atomic force microscopy(AFM),scanning electron microscopy(SEM),Leica optical microscopy(DM 2700M),semiconductor parameter tester(B1500A),and Keithley 2400.The main contents,results and and conclusions are as follows:1)The water-soluble chloride salts were selected as cationic reaction sources of CdS QDs,Bi2S3 QDs and MnS QDs,and sodium sulfide(Na2S)was used as sulfur source.Quantum dots are obtained under the conditions of near room temperature(40?,room temperature),atmospheric pressure,no inert gas protection and adding surfactants.The quantum dots with uniform dispersion,small size distribution and good crystallinity are obtained by adding different surfactants and choosing the optimum surfactant.2)The basic structure,morphology and optical properties ofsynthesized CdS QDs,Bi2S3 QDs and MnS QDs are studied.The average particle sizes of the CdS QDs,Bi2S3 QDs and MnS QDs are 4 nm,5 nm and 3.2 im,respectively.The CdS QDs,Bi2S3 QDs and MnS QDs are basically ellipsoidal,belbnging to wurtzite structure,orthogonal structure and hexagonal structure.By studying the optical properties of three kinds of quantum dots,it is found that the three kinds of quantum dots have strong absorption to ultraviolet light.So in the later stage,we will make three kinds of quantum dots into interdigital ultraviolet photodetectors,and study the photoelectric properties of three new types of photodetectors.3)The CdS QDs,Bi2S3 QDs and MnS QDs are fabricated into interdigital ultraviolet photodetectors to study their photoelectric properties.It is found by photoelectric performance test that CdS QDs have strong absorption of light less than 500 nm,the device response rate is greater than 0.3 ?A/W,and the device detection rate can reach 1.2x10~8 Jones.The ultraviolet photodetector made of Bi2S3 QDs has a high response rate of 104 mA/mW under 254 nm light.Under 254 nm light,the detection rate can reach 10~13 Jones,and when the voltage is 0.2 V,the detection rate can reach 1.17 x 10 5 Jones.The detection rate of MnS QDs ultraviolet photodetectors is basically stable at 109 Jones under 254 nm light.When V=-1.30 V,the highest detection rate is D*=2.12 x 1010 Jones.