First Principle Research On The InGaAs Photocathode

The low level light?LLL?night vision technology is the use of night sky radiation on the target object or the surface of the earth's own thermal radiation characteristics,and with the help of scientific instruments to observe the scene image which the core technology is the sensor.At present,the instrument of LLL night vision imaging is mainly composed of LLL image intensifier and infrared detector.Negative electron affinity InGaAs photocathodes have important application prospects in night-vision technology,forest fire prevention and severe climate detection.However,the research on the material properties and photoemission of InGaAs photocathode is not perfect,which will restrict its further development and need further investigate.In order to overcome these obstacles and meet the demands,using the first principles calculation method,the photoelectric properties of InGaAs photocathode are researched from the structure level.It provides a reference for the theoretical and experimental study of InGaAs photocathode.The main research works are shown as following:1.The adsorption properties of a Cs atom on the surface of InGaAs photocathodes were investigated.The work function,surface adsorption energy and electronstatedensitywerecomparedbetweenthesurfacesof In_0.53Ga_0.47As?100??₂?2×4?and Al_0.5Ga_0.5As?100??₂?2×4?.In combination with the experimental research method,the photocurrent change in the adsorption process of single Cs was measured by using the multi-information measurement which is designed by our team.At the same time,the optical properties of the Cs adsortion before and after on the photocathodes were researched and analyzed.It provides theoretical guidance for the preparation of photocathodes.2.The effect on photoelectric properties of Zn doping on InGaAs photocathodes were investigated.The geometric structure,charge distribution,formation energy and energy band structure of Zn substitutuion at In_0.53Ga_0.47As?100??₂?2×4?photocathode different sites were discussed.And the electronic structure and optical properties of Zn atoms acting on In_0.53Ga_0.47As?100??₂?2×4?photocathodes by means of substitution doping and interstitial doping were compared and analyzed,which provides a reference and theoretical basis for the practical application of photocathodes.3.The photoemission characteristics of InGaAs photocathodes were investigated.The transient reflectivity of GaAs and InGaAs models with delay time were detected by femtosecond pump-detection experiments.The spectral response and quantum efficiency of two kinds of InGaAs photocathodes with fixed and variable In component in emitter layer were discussed.And the results provide a reference for the design of high efficiency InGaAs photocathode materials.