Control of the interface shape in vertical Bridgman grown CdZnTe crystals for X-ray detector applications

The availability of large volume crystals with the same energy gap in melt-grown CdZnTe(CZT)is restricted due to the Zn segregation in CdTe hosts. We observed the migration of Zn in the solid phase along the positive temperature gradient direction both in-situ and post-growth temperature gradient annealing (TGA) of CZT. Diffusivity of Zn obtained from the in-situ TGA was approximately 10 −5 (cm 2 /s) order and completely different mechanism with that of post-growth. The CZT ingots obtained through in-situ TGA have uniform Zn and resistivity of 10 10 Ω•cm orders. The CZT detectors fabricated from in-situ TGA applied ingots exhibit 10 % of energy resolution for 59.5 keV peak of 241 Am.

show abstract

“…In this case, Zn composition along the growth direction follows the classical segregation law as shown in Fig. 2 [9].…”

Section: Resultsmentioning

confidence: 91%

“…It affects the doping profile and the ingot uniformity of materials grown from the melt [4]. Generally accepted segregation coefficient of Zn in a CdTe host is 1.3 although its values can vary from from 1.05 to 1.6 depending on the growth method and the Zn content [1,4,5,6,7,8,9].…”

Section: Introductionmentioning

confidence: 99%

Overcoming Zn segregation in CdZnTe with the temperature gradient annealing

Kim

Bolotnikov

Camarda

et al. 2016

Journal of Crystal Growth

View full text Add to dashboard Cite

show abstract

“…SLM stainless steel 316L microstructure has been affected by many factors including ingredients of the alloy, interfacial energy, temperature gradient and pyroconductivity (Flemings, 1980 and Zappettini et al , 2012) as shown in Figure 13. And among all these, pyroconductivity is the main factor which affects the microstructure and properties of the SLM overhanging structure; its change directly affects the thermal conduction direction and solidification rate, and in turn, the changes of the thermal conduction direction and solidification rate will result in great transformation of the overhanging structure in the molten pool size, solidification direction and microstructure when compared with the matrix (Zappettini et al , 2012).…”

Section: Resultsmentioning

confidence: 99%

Research on the microstructure and properties of the overhanging structure formed by selective laser melting

Sun

Yang

et al. 2017

RPJ

View full text Add to dashboard Cite

Purpose This paper aims to analyze the different between matrix and overhanging structure and indicate the laws and mechanism of overhanging structure formed by selective laser melting (SLM). Design/methodology/approach This paper includes processing the matrix and overhanging structure with optimized parameters and analyzing the microstructure and properties of matrix and overhanging with OM, SEM, XRD etc. so as to analyze and reveal the laws and mechanism of overhanging structure formed by SLM. Findings The solidification of overhanging structure begins from the structure’s edge and extends to its center; the distribution of the Cr with a diameter of 250 nm in the Fe matrix is uniform; the grain in the overhanging structure is growing faster than the grain in the matrix. The overhanging structure mainly composed by austenite has no apparent layer. Moreover, the microhardness of the overhanging structure is 258.6-294.0 Hv0.3, smaller than the microhardness of the matrix which is 236.4-300.9 Hv0.3. Originality/value This paper clarifies how to manufacture overhanging structure and non-overhanging structure matrix with optimized parameters, analyzes the microstructures and compares the properties of both overhanging structure and non-overhanging structure “matrix”, so as to analyze the reasons for the forming of the overhanging structure, which in turn lauds basic data foundation for the theoretical studies in the future.

show abstract

“…Bridgman furnace [11][12][13][14]. Cd 1-x Zn x Te (x=10%) crystals of 4.8 cm in diameter and about 7 cm in length were grown in cylindrical quartz ampoules having a conical tip.…”

Section: Numerical Modelmentioning

confidence: 99%

“…Good quality CZT crystals were grown by the encapsulated vertical Bridgman technique in a three zone furnace. The experimental technique is described in [11][12][13][14]. Before growth, the charge with a zinc concentration of 10% was doped with indium, with the aim of getting high resistivity CZT used for X-ray detector applications.…”

Section: Introductionmentioning

confidence: 99%

Numerical and experimental investigation of CdZnTe growth by the boron oxide encapsulated vertical Bridgman method

Stelian

Calestani

Velázquez

et al. 2021

International Journal of Heat and Mass Transfer

Self Cite

View full text Add to dashboard Cite

Cadmium zinc telluride crystals of 4.8 cm in diameter grown by the boron oxide encapsulated vertical Bridgman technique exhibit good structural quality with large grains and low dislocation density. However, the ingots contain Te inclusions, which are trapped at the growth interface during the crystallization process.Global modeling of the furnace was applied in order to investigate the temperature gradients and the evolution of the growth interface shape in this system. Transient computations, which include the crucible movement, show that the crystal-melt interface is concave toward the melt in the conical part of the ampoule, then becomes convex during the growth in the cylindrical part of the ampoule. Concave shapes of the interface and very homogeneous temperature distribution at the beginning of the solidification process promote the growth of a polycrystalline material. A novel hypothesis explaining the mechanism of grains formation at the ampoule tip was formulated. Our calculations show that the anomalous Zn segregation is due to the poor solute mixing at the beginning of the solidification process. The modeling of the standard growth process reveals very low vertical temperature gradients in the crystal (2-4 K/cm). Such low temperature gradients are 2 not favorable to eliminate the Te inclusions in the as grown crystal. A numerical model was employed to analyze the temperature field influence on the migration/size reduction of Te inclusions.

show abstract

Control of the interface shape in vertical Bridgman grown CdZnTe crystals for X-ray detector applications

Cited by 10 publications

References 22 publications

Overcoming Zn segregation in CdZnTe with the temperature gradient annealing

Overcoming Zn segregation in CdZnTe with the temperature gradient annealing

Research on the microstructure and properties of the overhanging structure formed by selective laser melting

Numerical and experimental investigation of CdZnTe growth by the boron oxide encapsulated vertical Bridgman method

Contact Info

Product

Resources

About