Preliminary results of characterization of CdZnTe crystals grown by the Davidov-Markov method

This paper presents the technology of CdZnTe crystal growth via the Davidov-Markov method, which allows the production of crystals with a large surface area, high resistivity and acceptable charge-carrier transport characteristics. For material characterization planar detector structures with an area of 5 mm x 5 mm and a thickness of 3 mm were fabricated. Estimates of the (μτ)_e values yielded results of (2 6)·10^-4 cm²/V. The (μτ)_p values for holes did not exceed 10^-5 cm²/V. Acceptable material homogeneity was found. The current-voltage characteristics of the crystals were measured at room temperature and exhibited linear behavior in a voltage range of up to 1 kV. The value of the specific resistance was about 10¹¹ Ohm-cm. The energy resolution of the planar CdZnTe detectors was 6.8 keV at 59.6 keV. A strip detector was fabricated from a 20.7 mm x 20.7 mm x 3.2 mm crystal. The detector topology consisted of 16 strips, a guard ring and a steering grid. The leakage current did not exceed 2 nA for a voltage of 100 V and a strip-pad area of 1.6 mm². The parameter distribution from strip to strip was homogeneous. The spectra of several radionuclide sources were measured by the individual strips of the anode side. Energy resolutions of 3.5, 10 and 40 keV were obtained at energies of 59.6,122 and 662 keV, respectively.