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Cadmium zinc telluride (CZT) is an ideal material for room temperature nuclear radiation detection, but CZT crystals of high quality and low defects concentration are difficult to obtain. Therefore, in order to improve the performance of the CZT detector, the working conditions of the CZT detector could be appropriately changed to make the internal electric field of the CZT detector close to uniform distribution so as to improve the electron transport performance. In this paper, alpha induced transient charge analysis has been used to study the internal electric field of the CZT detector, and deep level defects in CZT were linked with internal electric field distribution. Based on the process, a variety of deep level defects on electron trapping and detrapping by changing the temperature, the output waveform change of charge sensitive preamplifier (the pulse height spectra for alpha radiation at different temperatures) was observed, and then the effects of deep level defects on electron mobility (μ e), electron transport time (T R), the internal electric field, and the electron collection efficiency of the CZT detector were analyzed. The experimental results indicated that the influence of deep level defects was a main factor to the internal electric field in the range of −140 to 40 °C. As the temperature rises, the influence of these defects weakens, μ e and electron collection efficiency both increase, and internal electric field distribution tends to be uniform. Moreover, with the further increasing temperature (−40 to 20 °C), μ e decreased and internal electric field distribution became fluctuating, but electron collection efficiency was basically unchanged, which suggested that the influence of lattice vibration in the range of −40 to 20 °C turned to be the main factor. The above conclusions demonstrated that although the CZT detector has excellent room temperature detection ability, room temperature was not its optimal working temperature due to the influence of high concentration deep level defects. At −20 °C, the CZT detector presented the highest electron collection efficiency and maximum which limited the influence of deep level defects on electron transport, performing the optimal properties. [ABSTRACT FROM AUTHOR]

In this work, platinum (Pt) electrodes were deposited on CdZnTe wafers by electroless H 2 PtCl 4 solution and subsequently annealed at different temperature from 323 K to 473 K. Focused ion beam (FIB) imaging, transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), current-voltage (I–V) analysis and energy spectra under 241Am irradiation were adopted to investigate the effect of low-temperature rapid annealing on interface structure, electrical and carrier transport properties of Pt/CdZnTe samples. Single-crystal PtTe layer with [100] orientation and thickness of 20 nm was found in the interface between electroless Pt and CdZnTe wafer. The leakage current of the Pt/CdZnTe detectors at 200 V decreased from 212 nA cm−2 to 101 nA cm−2 after low-temperature rapid annealing, due to a decrease of voltage drop across the PtTe interface layer. The energy spectra and carrier transport performance of Pt/CdZnTe detectors suggested that the optimal annealing temperature was 423 K. The energy spectra of Pt/CdZnTe detector under 241Am showed that the FWHM was improved from 23.3% to 14.4%, while the full charge collection and mobility lifetime product of electrons increasing from 611 to 625 and 3.17 × 10−3 to 3.76 × 10−3 cm2 V−1 s−1, respectively. • Pt electrodes were deposited on CdZnTe wafers by electroless PtCl 4 and annealed at different temperature. • Single-crystal PtTe layer was found in the interface between electroless Pt electrode and CdZnTe wafer. • Annealing results in low voltage drop at PtTe interface layer, decreasing the leakage current of Pt/CdZnTe detector. • Electroless Pt/CdZnTe detector annealed at 423K shows the optimum energy spectral and carrier transport properties. [ABSTRACT FROM AUTHOR]

The performance of CdZnTe detectors is not only influenced by the growth of crystal, but also by the quality of the interface layer between the crystal and the electrode. A model of CdZnTe detector with metal–semiconductor–metal structure is developed to investigate the effects of the interface on the space charge and electric field distribution. Atomic force microscopy, current–voltage (I–V) analysis, and energy spectra under 241Am irradiation are adopted to investigate the effects of argon (Ar) plasma treatment on the interface and performance of CdZnTe detectors experimentally. The simulation results show that the interface layer with low density of surface state and thin thickness can form a more uniform space charge and electric field distribution. Due to the decrease of voltage drop across the interface, the leakage current at 200 V of CdZnTe detector with Ar plasma treatment is reduced from 159 to 44 nA cm−2, and the full‐width at half‐maximum under 241Am is improved from 9.3% to 8.2%, as compared to conventional Br‐MeOH treatment. [ABSTRACT FROM AUTHOR]

The Frisch-grid CdZnTe detector is a kind of unipolar detector, which can solve the problem of low resolution of planar CdZnTe detectors caused by the poor charge transport of holes. In this paper, high-quality CdZnTe crystals grown by traveling heater method were adopted to develop Frisch-grid CdZnTe detectors. The Geant4 software was adopted to simulate the interaction process of various γ -rays in CdZnTe detectors with different thickness. The Comsol software was used to simulate the structural and material parameters on the weighting potential and energy spectra of Frisch-grid CdZnTe detectors. According to the simulation results, the Frisch-grid CdZnTe detectors were fabricated, and the energy spectra of the detectors under different bias and shaping time were studied experimentally. The 4 × 4 array module of Frisch-grid CdZnTe detectors was designed, whereby the detection efficiency and energy spectra of the array module were studied with the Rena-3 readout ASIC. [ABSTRACT FROM AUTHOR]