Preparation And Performance Research Of CdMnTe Crystal Nuclear Radiation Detector

Cadmium manganese telluride(Cd_1-xMn_xTe or Cd Mn Te,hereinafter referred to as CMT)crystals are very similar to Cd Zn Te in terms of electronic energy band structure and semiconductor properties,and perform better in some aspects.Therefore,CMT crystals have become a room temperature nuclear radiation detector One of the ideal materials.High-quality crystals are the basis for the preparation of devices with excellent performance.At present,in terms of CMT crystal growth,many researchers have conducted systematic and comprehensive research and have been able to grow high-quality crystals.However,there is relatively little research on the preparation of detectors.This paper mainly studies the preparation and performance of CMT planar detectors based on the work of previous people,hoping to accumulate some experience in the preparation of CMT detectors.The specific work is carried out from three aspects:crystal performance research,detector preparation and detector performance characterization.In the experiment,through the I-V test under different electric（bias）voltages,the relationship between resistivity and voltage was fitted,and the true resistivity of the crystal was 5.01×10⁹Ω·cm.Under the condition of obtaining real resistivity,the leakage current of the material is the smallest.Based on the I-V curve test of the detector under the electric field condition of（0～3000）V/cm,the experiment found that the mutation of the curve is caused by the change of the conduction mechanism through the Poole-Frenkel（or PF）effect analysis.The experiment also analyzed the I-V curve in the temperature range of 220K-300K and found that the resistivity increased exponentially with the decrease of temperature.According to the dependence of resistivity and temperature,the Fermi energy level was pinned in the middle of the forbidden band.According to the thermal electrode current test（TSC）experiment,the defect levels in the crystal energy levels are 0.25e V,0.58 e V and 0.63e V,and the Fermi level is 0.75e V.The ultraviolet-visible-near infrared absorption spectrum and infrared transmission analysis show that the quality of the CMT crystal used in the experiment has good optical properties.Under the electric field intensity of 1000V/cm at room temperature,the energy resolution of the 5×5×3（mm³）single-plane detector for uncollimatedαparticles（5.48 Me V）is 27.5%.Alpha particle spectrum peaks include noise peaks,X-ray peaks,medium scattering peaks,reflection peaks,Compton platforms,cavity tailing,and omnipotent peaks.At the same time,the transport performance of the carrier is characterized,and the mobility and life of the carrier are calculated.I-V characteristic analysis of the annealed Au-CMT electrode revealed that the leakage current of the device after annealing was reduced.Compared with the unannealed Au-CMT,the ohmic contact characteristics between the electrode and CMT were improved.Au-CMT’s current-time（I-t）test found that annealing helps to stabilize the leakage current and can reduce the noise peak caused by the leakage current.The energy resolution of alpha particles（5.48 Me V）after annealing was17.1%,which was greatly improved on the basis of 27.5%before annealing.