High-Purity CdMnTe Radiation Detectors: A High-Resolution Spectroscopic Evaluation

Yang

Nuclear Instruments and Methods in Physics Research Section A:

et al. 2015

a b s t r a c tBridgman-grown cadmium zinc telluride (CdZnTe or CZT) and cadmium manganese telluride (CdMnTe or CMT) crystals often have Te inclusions that limit their performances as X-ray-and gamma-raydetectors. We present here the results of post-growth thermal annealing aimed at reducing and eliminating Te inclusions in them. In a 2D analysis, we observed that the sizes of the Te inclusions declined to 92% during a 60-h annealing of CZT at 510 1C under Cd vapor. Further, tellurium inclusions were eliminated completely in CMT samples annealed at 570 1C in Cd vapor for 26 h, whilst their electrical resistivity fell by an order of 10 2 . During the temperature-gradient annealing of CMT at 730 1C and an 18 1C/cm temperature gradient for 18 h in a vacuum of 10 À 5 mbar, we observed the diffusion of Te from the sample, so causing a reduction in size of the Te inclusions. For CZT samples annealed at 700 1C in a 10 1C/cm temperature gradient, we observed the migration of Te inclusions from a lowtemperature region to a high one at 0.022 μm/s. During the temperature-gradient annealing of CZT in a vacuum of 10 À 5 mbar at 570 1C and 30 1C/cm for 18 h, some Te inclusions moved toward the hightemperature side of the wafer, while other inclusions of the same size, i.e., 10 mm in diameter, remained in the same position. These results show that the migration, diffusion, and reaction of Te with Cd in the matrix of CZT-and CMT-wafers are complex phenomena that depend on the conditions in local regions, such as composition and structure, as well as on the annealing conditions.

Section: Introductionmentioning

confidence: 99%

Post-growth annealing of Bridgman-grown CdZnTe and CdMnTe crystals for room-temperature nuclear radiation detectors

Yang

Nuclear Instruments and Methods in Physics Research Section A:

et al. 2015

Hard X-Ray, Gamma-Ray, and Neutron Detector Physics XXI

“…It was found in the late 1990s that the crystal quality and electron charge colletion improves with the transition from CdTe to Cd1-xZnxTe (x ≈ 0.1-0.2) solid solution, but other problems remain. The new search for X/γ-ray detector materials continues, and Cd1-xMnxTe solid solutions deserve special attention due to their material properties [8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Mechanisms contributing to dark current across metal/CdMnTe/metal structures

Sklyarchuk

Fochuk

Solodin

et al. 2019

Self Cite

Studies of the electro-physical properties of n-type semi-insulating indium-doped Cd(Mn)Te crystals with a resistivity ~ (4-5)×10 10 Ohm×cm at T = 300 K were carried out. Structures with both ohmic (In/Cd(Mn)Te/In) and rectifying (Ni/Cd(Mn)Te/In) contacts were fabricated and tested. It was found that in the case of the Ni/Cd(Mn)Te/In structure, the charge transport can be explained by the generation of currents in the space-charge region and the spacecharge limited current (SCLC) at high voltages, while Ohm's law is valid only at the initial section of the volt-ampere (I-V) curve. Calculations of the dependence of the generation current on the voltage according to the Sah-Noyce-Shockley model were performed. For the In/Cd(Mn)Te/In structure, we observed the initial part of the I-V curve obeys Ohm's law, and the SCLCs with participation of deep centers (traps) in the semi-insulating crystal were observed at greater voltages. The concentration of deep centers (Nt ~ 7.4×10 10 cm -3 ) responsible for the trap mechanism in SCLC In/Cd(Mn)Te/In structures was calculated. The energy position Et1 of the deep level was determined (calculated from the valence band edge at Et1= 0.89-0.9 eV). We demonstrated that SCLC was the main mechanism limiting the operating voltage and, consequently, a major factor in the performance and use of Cd(Mn)Te-based ionizing radiation detectors with ohmic contacts.

Crystal Research and Technology

“…[1][2][3]. The CdMnTe detector was demonstrated to be a good candidate to compete with CdTe and Cd 1-x Zn x Te detectors in nuclear detection applications, such as: nuclear medical, national security, environmental safety, and space science [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…Cd 1 ‐x Mn x Te (CdMnTe) is a new compound semiconductor for room‐temperature X‐ and γ‐ray detector applications, with advantages of large band gap (1.53 ∼ 2.54 eV), high average atomic number (∼ 50) and high density (5.2 ∼ 5.9 g/cm 3 ), etc. . The CdMnTe detector was demonstrated to be a good candidate to compete with CdTe and Cd 1 ‐x Zn x Te detectors in nuclear detection applications, such as: nuclear medical, national security, environmental safety, and space science .…”

Section: Introductionmentioning

confidence: 99%

Comparison of cadmium manganese telluride crystals grown by traveling heater method and vertical Bridgman method

Lai

Zhang

Wang

et al. 2015

In this paper, the CdMnTe crystals were grown by the Travelling Heater Method (THM) and the Vertical Bridgman (VB) method, respectively. The crystal properties, including the Mn axial distribution, impurity concentrations, resistivity, Hall effects and energy response spectra, were characterized and compared. The results shown that the CdMnTe crystal grown by the THM had more uniform Mn distribution and lower impurity concentrations compared to the crystal grown by VB method. The resistivity of CdMnTe grown by THM was (1.5 ß 8) × 10 10 .cm, while the resistivity of CdMnTe grown by VB was 10 7 ß10 8 .cm. TheIn dopant distributed uniformly throughout the crystal ingot grown by THM with the doping concentration of 0.6-0.7 ppm, while the In dopant concentration throughout the crystal grown by VB method is in the range of 1.31-2.4 ppm. Hall measurements revealed that the conductivity of the THM grown crystal was weak n-type conductivity and the VB grown crystal was p-type conductivity. A planar CdMnTe detector from the THM grown crystal showed a resolution of 8% of the 241 Am radiation at 59.5 keV peak, however, no energy response was revealed with the CdMnTe detector by the VB method. The results demonstrate that CdMnTe crystal grown by THM have better crystal quality and detector properties compared to that by VB method.