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CZT Thesis

The CZT Thesis section features research theses focused on Cadmium Zinc Telluride (CZT) materials and their applications
Investigation of seeded vertical gradient freeze (VGF) growth of CdZnTe bulk crystals
Date: November 1, 2025 | Author: Özden B. Balbaşı | Hits: 77
Due to the requirement for superheating above the melting point in the homogenization process of CdZnTe material, complete seed melting remains as a significant problem for the seeded vertical gradient freeze (VGF) growth of CdZnTe. In addition, due to the typical low single crystal yields in VGF growth of CdZnTe, obtaining single crystal seed material with desired geometries could be considered as a challenge. In this study, single crystal CdZnTe seeds of cylindrical geometry with 10 mm diame ...
Investigation on method of reducing surface leakage current of the CdZnTe photoconductive detector with MSM structure
Date: October 31, 2025 | Author: Jiahua Min | Hits: 7247
The surface leakage current (SLC) of CdZnTe is an important factor affecting detection performance. In this work, we established a two-dimensional model of metal-semiconductor-metal (MSM) structured CdZnTe with a low-resistance layer on the surface. The composition of SLC and the distribution of the internal electric field are analyzed by simulation. The study found that the change of electrode size will change the contribution of SLC from cathode, anode and side surfaces. With the increase of ...
Radiation effects induced by the energetic protons in 8x8x32 mm3 CdZnTe detectors
Date: October 31, 2025 | Author: A. Bolotnikov | Hits: 159
CdZnTe (CZT) detectors have been used in the past and are being actively considered for future gamma-ray space telescopes. One of the challenges of operating CZT detectors in low Earth orbit is radiation damage caused by energetic protons. Previous studies concluded that fluences of 108 -109 p/cm 2 are sufficient to cause shifting of peak positions and degradations of energy resolution. Degradation of detectors after proton irradiation has been extensively investigated to determine their radia ...
Optical and dielectric investigations on Ag- CdZnTe hybrid polyvinyl alcohol freestanding films
Date: October 30, 2025 | Author: Siby Mathew | Hits: 26
Hybrid freestanding films of polyvinyl alcohol incorporated with silver and CdZnTe quantum dots were synthesized. The effect of varying silver concentration on optical and dielectric properties were studied. Structural and morphological analysis of hybrid films were done using X-ray diffraction and transmission electron microscopy. Optical parameters like absorption coefficient, extinction coefficient, refractive index, optical bandgap, urbach energy and optical conductivity were studied for t ...
Optimization study of the electrode design of a 5 mm thick orthogonal-strip CdZnTe detector system
Date: October 30, 2025 | Author: Ali Murteza Altıngün | Hits: 162
The geometry of electrodes is one of the most important factors in determining the performance of orthogonal-strip detectors. The aim of this work is to study the performance of a 5 mm thick cross-strip CdZnTe detector with different electrode widths. Our study consists of two main parts, simulations and experiments. We utilized four different anode sizes ranging from 0.1 mm to 0.6 mm. The anodes were interspersed with steering electrodes with varying sizes from 0.3 mm to 0.85 mm. The maximum ...
Achieving sub-pixel position resolution and sub-millimeter depth resolution using a pixelated CdZnTe detector
Date: October 29, 2025 | Author: Chao Wang | Hits: 35
The CdZnTe detector, a room-temperature semiconductor detector, has many applications for nuclear safety and nuclear medicine because of its high energy resolution and small size when compared with scintillator detector and high purity Germanium detector respectively. Radionuclide imaging is one of the most important applications that requires adequate three-dimensional position resolution. In this work, we used a CdZnTe crystal from eV Products with a pixelated anode to achieve approximately ...
Passivation effect on large volume CdZnTe crystals
Date: October 29, 2025 | Author: K. Kim | Hits: 6205
Several cadmium zinc telluride (CZT) crystals were fabricated into radiation detectors using methods that included slicing, dicing, lapping, polishing, and chemical etching. A wet passivation with sodium hypochlorite (NaOCl) was then carried out on the Br-etched detectors. The Te-rich layer on the CZT surface was successfully compensated to the Te oxide layer, which was analyzed with X-ray photoelectron spectroscopy data of both a Br-etched crystal and a passivated CZT crystals. We confirmed t ...
Study on the density of trap states between CdZnTe and passivation layer based on MIS structure
Date: October 28, 2025 | Author: Xiaoyan Liang | Hits: 35
CdZnTe room temperature nuclear radiation detectors are widely used in the fields of homeland security, medical imaging and astrophysics. In the Cd1-xZnxTe radiation detector, the purpose of passivation is to reduce dark current and improve stability. In this study, CdZnTe etched by bromine-methanol (BM) was treated with standard H2O2 and NH4F passivation process. With the help of TEM and EDS measurement results, the thickness of the passivation layer ranges from 126 nm to 183 nm, and X-ray ph ...
Effect of low-temperature rapid annealing on structural and electrical properties of electroless platinum contacts on CdZnTe detectors
Date: October 28, 2025 | Author: Jijun Zhang | Hits: 56
In this work, platinum (Pt) electrodes were deposited on CdZnTe wafers by electroless H2PtCl4 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 ...
Identification of twin and nanoscale Te precipitations in CdZnTe crystals grown by vertical gradient method with HRTEM
Date: October 27, 2025 | Author: Siwei Tang | Hits: 26
CdZnTe (CZT) has attracted much attention in nuclear detection field attribute to its high detection efficiency, high energy resolution and room-temperature operation. In this work, the CdZnTe samples were prepared by Vertical gradient method. High-resolution transmission electron microscopy (HRTEM) was used to investigate the nanoscale defects in CZT crystals. It is found that the twins are symmetric about the {111} plane, and the dislocations and stacking faults locate around the twin bounda ...
Effect of different annealing conditions on CdZnTe thin films for absorber layer applications
Date: October 27, 2025 | Author: M.S. Dhaka | Hits: 38
The Silicon based single junction and perovskite solar cells have demonstrated high efficiency but Silicon based cells suffer from the drawback of higher cost and perovskite solar cells are not stable and degradable in environment. The thin film based CIGS and CdTe cells have achieved efficiency of more than 22% but, particularly, the CdTe thin film solar cells require a suitable back contact which can be obtained by doping of Zn element in CdTe. The grain growth in CdTe-based films is attaine ...
Types and origin of surface defects induced by post-growth annealing of CdZnTe and CdMnTe crystals
Date: October 26, 2025 | Author: Pengfei Yu | Hits: 46
In this paper, several kinds of defects induced by post-growth annealing were studied. The type, morphology, origin and formation mechanism of these defects were analyzed and discussed. The defects were characterized by a number of testing methods. The results indicated that high temperature (>973 K) and long time (240 h) annealing were harmful to CdZnTe and CdMnTe crystals, which led to thermal etch pit and surface and internal oxidation. The phenomena of thermal migration of Te inclusions ...
Effectiveness of parylene coating on CdZnTe surface after optimal passivation
Date: October 26, 2025 | Author: K. Kim | Hits: 25
Parylene coating was adopted on CdZnTe (CZT) detector as a mechanical protection layer after wet passivation with hydrogen peroxide (H2O2) and ammonium fluoride (NH4F). Wet chemical passivant lose their effectiveness when exposed to the ambient conditions for a long time. Parylene coating could protect the effectiveness of passivation, by mechanically blocking the exposure to the ambient conditions. Stability of CZT detector was tested with the measurement of leakage current density and respon ...
γ-ray energy spectrum response tailing in CdZnTe detector
Date: October 25, 2025 | Author: Chunzhi Zhou | Hits: 378
Affected by the characteristics of carrier transport, the γ-ray energy spectrum of the cadmium zinc telluride (CZT) detector usually has a low-energy tail phenomenon The traditional γ -ray energy spectrum response simulation model is mainly aimed at detectors with a uniform internal electric field, not suitable for non-uniform internal electric fields, and cannot accurately characterize the low-energy tailing phenomenon of the γ -ray energy spectrum of CZT detectors. In this study, for the ...
Effects of annealing in Te2 atmosphere on photoelectric properties and carrier transport properties of CdZnTe films
Date: July 17, 2025 | Author: Kun Cao | Hits: 78
CdZnTe (CZT) epitaxial films were deposited on GaAs substrates by closed spaced sublimation. In order to reduce the adverse effects of point defects and dislocations in the film on its properties, CZT films were annealed at 400 °C in Te2 atmosphere at different times. The I–V test and energy spectrum show that the resistivity of CZT films increased from 109 Ω cm to 1010 Ω cm, and the electron mobility lifetime product (μτ)e increased from 10−5 cm2 V−1 to 10−4 cm2 V−1. According ...
Monte-Carlo simulation for detecting neutron and gamma-ray simultaneously with CdZnTe half-covered by gadolinium film
Date: July 17, 2025 | Author: B. Park | Hits: 72
Neutron is an indirectly ionizing particle without charge, which is normally measured by detecting reaction products. Neutron detection system based on measuring gadolinium-converted gamma-rays is a good way to monitor the neutron because the representative prompt gamma-rays of gadolinium have low energies (79, 89, 182, and 199 keV). Low energy gamma-rays and their high attenuation coefficient on materials allow the simple design of a detector easier to manufacture. Thus, we designed a cadmium ...
Electro and electro-photo plasticity of CdZnTeSe and CdZnTe
Date: July 16, 2025 | Author: Václav Dědič | Hits: 87
We studied the influence of applied bias on of the Vickers microhardness HV 0.025 of CdZnTeSe and CdZnTe semi-insulating samples without and with the illumination of light at 870 nm. We observed that a small applied bias results in the hardening of the material. The effect is strongest at a bias of ± 0.5 V and is further strengthened by additional illumination. We suggest that the observed positive electro and electro-photo plastic effects in CdZnTeSe and CdZnTe can be explained by an increas ...
Spectrally-dependent positive and negative photo-plastic effects in CdZnTe and CdZnTeSe
Date: July 16, 2025 | Author: Václav Dědič | Hits: 81
We studied the Vickers microhardness HV0.025 of CdZnTe and CdZnTeSe samples upon illumination with quasi-monochromatic light with wavelengths ranging between 750 and 1540 nm. We observed that light with a wavelength close to or above the bandgap of the samples results in a positive photo-plastic effect (hardening), and light in the spectral range well below the band gap can lead both to positive or negative effects depending on the parameters of deep levels in the bandgap. We performed measure ...
Production of detector grade CdZnTe crystal with VGF furnace by analyzing segregation of Zn and In
Date: July 15, 2025 | Author: Mustafa Ünal | Hits: 118
Production of CdZnTe crystals for radiation detector applications through Bridgman and Vertical Gradient Freeze (VGF) techniques is challenging in many aspects. Due to the structural characteristics of CdZnTe, it is not possible to obtain a large single crystalline ingots from the melt growth technique. In addition, the segregation of dopants and Zn decrease the yield significantly. In order to achieve detector-grade CdZnTe crystals, zinc segregation behavior should be fully understood, and op ...
Study on relaxation phenomenon of CdZnTe photon counting detectors in X-ray imaging
Date: July 15, 2025 | Author: Yingrui Li | Hits: 35
During X-ray scanning imaging, the X-ray dose received by CdZnTe photon counting detectors varies dynamically because of the different absorption coefficients that occur at different locations in the object being imaged. This paper explores the phenomenon of count rate relaxation in CdZnTe detectors during X-ray dose mutations and studies the intrinsic relationship of this phenomenon with the polarization effect. The characterization of the count rate relaxation processes of CdZnTe detectors a ...
Feasibility study of CdZnTe and CdZnTeSe based high energy X-ray detector using linear accelerator
Date: July 14, 2025 | Author: Jeongho Kim | Hits: 74
CdZnTeSe (CZTS) has attracted attention for applications in X- and gamma-ray detectors owing to its improved properties compared to those of CdZnTe (CZT). In this study, we grew and processed single crystals of CZT and CZTS using the Bridgeman method to confirm the feasibility of using a dosimeter for high-energy X-rays in radiotherapy. We evaluated their linearity and precision using the coefficient of determination (R2) and relative standard deviation (RSD). CZTS showed sufficient RSD values ...
Morphology-property relationships of CdZnTe films prepared via radio frequency magnetron sputtering
Date: July 14, 2025 | Author: Dongmei Zeng | Hits: 26
The polycrystalline CdZnTe films are promising material for fabrication of X-ray detection and solar cells. In this study, a pebble-like grain, hexagonal grain and worm-like grain of CdZnTe films were prepared via radio frequency magnetron sputtering. The morphology and properties of CdZnTe films were then characterized using atomic force microscopy, 2-D grazing-incidence wide-angle X-ray scattering, Raman spectra, transmission spectra and current–voltage curves. Accordingly, the CdZnTe crys ...
The Growth Pits Filling Mechanism of CdZnTe Epitaxial Film Prepared by Close-Spaced Sublimation Based on the First-Principles Calculation
Date: July 13, 2025 | Author: Kun Cao | Hits: 123
The preparation of high quality II-VI semiconductor single crystal still is a challenging task. The II-VI ternary compound Cd1-xZnxTe is an outstanding candidate for room temperature nuclear radiation detectors. Therefore, the epitaxial mechanism of its film is profound to clarify for accurate growth regulation and quality improvement. However, determining the essence of epitaxial growth remains challenge only using experiments to explore the effects of growth conditions on film epitaxy. In th ...
Capability demonstration of a 3D CdZnTe detector on a high-altitude balloon flight
Date: July 13, 2025 | Author: Sara Abraham | Hits: 29
In collaboration between the University of Michigan and Los Alamos National Laboratory, a 3D position-sensing CdZnTe (CZT) detector prototype was built and integrated into a high-altitude balloon platform to evaluate its performance in a space-like mixed-radiation environment. The detector prototype, Orion Eagle, was designed to operate in near-vacuum environments without any temperature regulation. Orion Eagle was hand-launched from NASA’s Columbia Scientific Balloon Facility (CSBF) at Fort ...
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