Title :
Improving and Characterizing (Cd,Zn)Te Crystals for Detecting Gamma-Ray Radiation
Author :
Davydov, L. ; Fochuk, P. ; Zakharchenko, A. ; Kutny, V. ; Rybka, A. ; Kovalenko, N. ; Sulima, S. ; Terzin, I. ; Gerasimenko, A. ; Kosmyna, M. ; Sklyarchuk, V. ; Kopach, O. ; Panchuk, O. ; Pudov, A. ; Bolotnikov, A.E. ; James, R.B.
Author_Institution :
Nat. Sci. Centre, Kharkov Inst. of Phys. & Technol., Kharkiv, Ukraine
Abstract :
Cd0.9Zn0.1Te ingots were synthesized from pure components (6N purity Cd, Zn, and Te with In as the dopant) and subsequently grown from the melt under an argon overpressure. Graphite crucibles (with and without an inner coating of pyrolytic BN) were used. The temperature gradient in the solidification zone was 7-30 K/cm, and the growth rate was 0.6-1.0 mm/hour. We investigated the chemical composition, structure, and electrical properties of the as-grown crystals, and established relationships between the crystal properties and the growth conditions. The bottom, middle, and top of the ingots had n-type conductivity, but slightly different properties. Resistivity reached a maximum in the middle of the ingots ((2.5 - 5.0) ×1010 Ohm-cm), and was less at the edges ~ 0.8 ×1010 Ohm-cm. The value of the bandgap was minimal in the middle of the ingots (~ 1.5 eV), and 1.53-1.55 eV at the edges. The compensation degree ( Nd/Na) of the energy level responsible for the low dark conductivity showed a maximum value at the bottom of the ingots (~ 60 - 90%), and a minimum in the middle part (1-2%). The crystals were then used to fabricate Cd(Zn)Te detectors for gamma-ray radiation.
Keywords :
II-VI semiconductors; cadmium compounds; crystal growth from melt; dark conductivity; electrical resistivity; energy gap; gamma-ray detection; ingots; semiconductor growth; solidification; wide band gap semiconductors; zinc compounds; (CdZn)Te crystals; Cd0.9Zn0.1Te; argon overpressure; bandgap; chemical composition; compensation degree; crystal properties; dark conductivity; electrical properties; energy level; gamma-ray radiation; graphite crucibles; growth rate; ingots; n-type conductivity; resistivity; solidification zone; temperature gradient; Crystallization; Detectors; Gamma-rays; Nickel; Resistance; Zinc; CdZnTe seeded growth; In doping; Zn uniformity; semiconductor radiation detectors; spectroscopic characteristics; surface barrier detector;
Journal_Title :
Nuclear Science, IEEE Transactions on
DOI :
10.1109/TNS.2015.2448939