Optical-Electrical Properties Enhancement Of PbSe Materials And Infrared Detector

In recent years,with the rapid development of optoelectronic materials and device technology,mid-infrared detector has a high application value in many military and civil fields.The properties of photosensitive detection materials directly affect the performance of mid-infrared detector.PbSe is a direct band-gap semiconductor material with narrow band-gap width.It has excellent optical and photoelectric properties and is very suitable for the photosensitive material of unrefrigerated mid-infrared photoconductive detector.Therefore,in this paper,by combining theoretical simulation and experimental operation,we carry out related researches on deposition and growth of PbSe thin film,optical-electrical properties enhancement of PbSe thin film,development of PbSe thin film infrared detector,etc.The main research work of the paper is as follows:1)The electronic structure and optical properties of PbSe bulk materials and PbSe thin films with different grain orientations are calculated by using the first principles theoretical calculation method based on density functional theory.Then, the difference of interface properties between PbSe thin films and different substrates is analyzed by thermodynamic method.The effects of substrate deposition and film thickness on microstructure and optical properties of PbSe thin films are discussed.The calculation results show that the interface energy of PbSe film and single crystal fluoride substrate is low,which is easy to adsorb and grow. With the decrease of film thickness and microscopic strain in film,the band gap becomes narrow and the optical absorption edge is redshifted.2)Homogeneous PbSe thin films with stable structure and properties are prepared by chemical vapor deposition and vacuum evaporation deposition.The main grain orientation,grain structure,film thickness,optical absorption edge and other properties of the films are precisely regulated by controlling process parameters and improving experimental methods.The main grain orientations of PbSe films are[200]and[220],and the grain structures include cubic,acicular and spherical.The thickness of PbSe films can range from micron to nanometer,and the optical absorption edge is 4.8～5.3μm.3)By using sensitization treatment process,the dark resistance of PbSe thin films decreases by 33%,and the photoelectric sensitivity increases by 50%.By doping a certain amount of S element in the preparation of PbSe thin films,the optical absorption edge of the thin films can be regulated and the absorbance of the thin films can be increased.By plating periodic metal optical structure on the surface of PbSe thin films,the absorption spectrum of the thin film system presents the characteristics of narrow band and high absorption rate,which plays the role of band-pass filter,and the maximum absorbance of the narrow band absorption peak of the system reaches 95.8%.4)The structure of interfinger electrode and detector is designed,and PbSe thin film is assembled into mid-infrared photoconductive detector by sputtering,welding and other processes.The PbSe thin film mid-infrared detector prepared in this study can work stably at normal temperature,the peak response wavelength appears at 3.560μm,the corresponding peak current response is 6.886 m A/W,and the noise equivalent power density（white noise）per unit bandwidth is about 2×10^-25 A²/Hz.The normalized detection rate is 2.720×10⁹ cm·Hz^1/2·W^-1（Jones）.The PbSe thin film mid-infrared detector prepared in this study has good performance and can be used in gas detection,flame high temperature detection,infrared optical imaging and other fields.