Research On The Key Technology Of Cu₂Cd_xZn_1-xSnSe₄ Short-wave Infrared Detector Dark Current Reduction

Infrared photodetectors have been widely used in various industries,including medical diagnosis,night vision,water mist penetration,aviation,target recognition,and astronomy.This paper focuses on a new type of low-cost short-wave infrared detector with a response range covering the visible and near-infrared regions,that is,copper-cadmium-zinc-tin-selenium Cu2CdxZn1-xSnSe4(CCZTSe)short-wave infrared detector.CCZTSe belongs to the kesterite structural material.Because of its low cost,rich material content on the earth,and adjustable band gap characteristics,it has gradually become a good choice for new infrared photodetector materials.At present,the main problem of CCZTSe is that the dark current is too high,which will affect the detection rate of the device.In view of this,this paper analyzes the main sources of dark current and optimizes the device structure through SCAPS software,and provides theoretical guidance for the preparation of the device in the experiment based on the theoretical analysis results.The specific research content is as follows:1.The dark current components of CCZTSe thin film infrared detector(TFID)are analyzed by numerical simulation,and the main factors affecting the size of dark current are studied:Cd composition,absorption layer thickness,absorption layer carrier concentration,and interface state;The device structure is optimized,and barrier layers of MoO3,MoSe2 and MoS2 are introduced between the back contact electrode and P-CCZTSe,respectively.The simulation results show that the dark current of the device is reduced from 1.03nA/cm2 to 6.7×10-2nA/cm2 by introducing the barrier layer MoO32.The effect of the interface state on the dark current is simulated and the device preparation process is improved.The experiment starts with the growth and annealing process of the precursor film to improve the crystallinity of the film and reduce the dark current caused by the interface defects.The research results show that the introduction of NaF and Na diffusion into the CCZTSe film during the growth of the precursor is helpful to the crystallization of the film.The continuous introduction of H2Se during the annealing process also helps the crystallization of the film,and reduces the dark current from 7.32×104nA/cm2 to 1.5 × 104nA/cm2 of the device by reducing interface defects.3.The influence of the back contact barrier on the dark cur rent of the device is studied.The simulation introduces the back barrier layer to optimize the device structure.In the experiment,the back contact barrier is reduced from 0.45eV to 0.16eV by adding a thin MoS2 layer between the back contact electrode and ?-CCZTSe,and the corresponding dark current of the device is reduced from 1.5×104nA/cm2 to 7.72×102nA/cm2.