The Research On CdZnTe Crystal Growth And Processing Technology

Cadmium zinc telluride crystal has received more and more attention from researchers for its excellent room temperature nuclear radiation detection and infrared detection performance.Which in a molar ratio: 0.96:0.04:1 of cadmium zinc telluride crystal is used for the manufacture of high performance infrared long wave very long wavelength Hg Cd Te detectors epitaxial substrate material is particularly important.However,due to the high cost,low single crystal,small size and other issues of the Cd Zn Te growth,the use and popularization of high performance detector has been restricted.At present,the researchers at home and abroad often use the the Bridgman method to prepare the Cd Zn Te,and this method is easily to cause the larger of Cd vacancy defects and dislocation density of Cd Zn Te.Travelling heater method is a kind of advanced theory,which can significantly reduce the Cd vacancy,dislocation density,and improve the purity of the crystal.However,there are some difficulties in the growth of Cd Zn Te by THM,such as the place of seed crystal,and the difficulty of establishing a stable solution-growth layer.The main research contents are as follows:The coating parameters of chemical vapor deposition method is studied,and that is,1100℃,the volume of 3ml ethanol,vacuum pressure 3 ～ 6Pa,coating time 4 ～ 5h,cooling time 20 h,coating quality and repeatability is better.The relationship between the temperature gradient and the growth rate is analyzed,and a simple one-dimensional model is established.The establishment and calibration of temperature field,the Cd compensation control,and the process parameters for the synthesis of polycrystalline materials,are studied in the process of the growth of Cd Zn Te.The process parameters for the growth of Cd Zn Te crystal by vertical Bridgman method were studied,when the temperature gradient is 6.7℃/cm,the growth rate of1mm/h can obtain the higher resistivity of Cd Zn Te crystal.The technology of seed crystal THM method to grow Cd Zn Te crystal was studied.The crucible design of the Cd Zn Te growth by THM method and the seed crystal placement problem were solved.The experiment was carried out.Finally,the crystal ingot grown by THM method was obtained.By measuring the infrared transmittance,it is confirmed that the crystal quality of obtained by the THM method is better than that obtained by the Vertical Bridgman method,the average infrared transmittance of obtained by THM method reaches to 45%.The main innovations in this paper :1.A method is developed to control the evaporation rate of anhydrous alcohol by controlling the anhydrous alcohol consumption,and to improve the quality and success rate of the coating.2.Discovering a new method to improve the accuracy of temperature measurement,that is,through the MMB calibration of the temperature field,to improve the accuracy of furnace temperature measurement.3.A series of process parameters have been studied in the light of the preparation of Cd Zn Te crystal by seed crystal THM.The growth of Cd Zn Te crystal was successfully carried out by the T shaped crucible,which provided a reference for the growth of high quality crystals.