Ergunt, Yasin
Kabukçuoğlu, Merve Pinar
Balbasi, Ozden Basar
Yaşar, Bengisu
Kalay, Yunus Eren
Turan, Raşit
Parlak, Mehmet
The study of Cd1-xZnxTe (Cadmium Zinc Telluride) bulk-crystal growth and surface processing technology at the Middle East Technical University (METU) began in 2012. The initial R&D efforts were started with the growing of CdZnTe ingots up to a size of 15 mm in diameter in a three-zone vertical Bridgman furnace located in a limited laboratory area of 15 m2. Following promising development in terms of single crystal yield and the crystal growth process, a new vertical gradient freeze (VGF) multi-zone furnace setup was designed and developed to accommodate the production of 60 mm diameter CdZnTe ingots. The entire furnace setup is located in a newly founded 90 m2 laboratory named the METU Crystal Growth Laboratory (METU-CGL) in 2013. The laboratory is fully dedicated to the CdZnTe material growth and surface processing technology. Currently, METU-CGL is capable of producing 60 mm diameter CdZnTe ingots with one large grain and a few small grains. CdZnTe material is continuously grown in order to serve as either a substrate material (Cd0.96Zn0.04Te) for infrared detectors or an active material (Cd0.90Zn0.10Te) for X-ray/Gamma-ray detectors. As a typical yield, 2-3 oriented wafers per radial slice are retrieved from the grown ingots. The target wafer dimensions are 20 mm x 20 mm; however, larger or smaller crystals can be obtained based on the application of interest. The crystalline quality of the produced crystals is way below 50 arcsec of FWHM (Full width at half maximum) values from the DCRC (Double crystal rocking curves) measurements and the EPD (Etch-pit density) values are typically mid-104/cm2. Infrared (IR) transmission of the home-grown CdZnTe crystals is exceeding 60% and stays constant within 2-20 µm wavelength interval showing that the crystals have low density of inclusions and precipitates. Not only limited to CdZnTe bulk growth technology, the METU-CGL is also capable of slicing and surface processing technologies including optimized lapping, rough mechanical polishing, and performing final chemo-mechanical polishing steps with extreme care regarding surface roughness and subsurface damage. Achievable surface roughness values of produced wafers are well below 0.5 nm (Rrms). Various state-of-the-art characterization techniques including HRTEM (High-resolution transmission electron microscopy) and APT (Atom probe tomography) were conducted to study nanoscale defects in CdZnTe as a material property. This paper reviews many aspects of CdZnTe bulk-growth, surface finishing, and characterization technologies at METU-CGL as well as the laboratory infrastructure itself.


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Cadmium Zinc Telluride (Cd1-xZnxTe) has become a crucial material for X-ray and gamma ray detection due to its wide band-gap, high atomic number and high density, which offer high efficiency and sharp spectroscopic resolution at room temperature. In addition, due to being lattice matched, it can also be used as substrate for the epitaxial growth of HgCdTe that can be used for infrared detection with high resolution. Hence, increasing the single crystal yield of CdZnTe from the grown ingot gained importance ...
Production of High-Performance CdZnTe Crystals Grown by THM for Radiation Detection Applications
Ünal, Mustafa; Balbaşı, Özden Başar; Karaman, Mehmet Can; Genç, Ayşe Merve; Parlak, Mehmet; Turan, Raşit (2022-01-01)
© 2022, The Minerals, Metals & Materials Society.CdZnTe crystals are the perfect candidate to be used in room temperature x-ray and gamma-ray detection systems. Production of detector-grade crystals, on the other hand, is challenging due to the unique properties of the CdZnTe. CdZnTe crystals are soft-brittle materials and have high ionicity of bonds that makes the growth process challenging. Among several growth techniques, the travelling heater method (THM) is a preferred growth method to obtain high-qual...
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High quality of graphene is necessary for its applications at industrial scale production. The most convenient way is its direct growth on dielectrics which avoid the transfer route of graphene from metal to dielectric substrate usually followed by graphene community. The choice of a suitable dielectric for the gate material which can replace silicon dioxide (SiO2) is in high demand. Various properties like permittivity, thermodynamic stability, film morphology, interface quality, bandgap and band alignment...
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We have achieved significant improvement in the electrical performance of the InAs/GaSb midwave infrared photodetector (MWIR) by using atomic layer deposited (ALD) aluminium oxide (Al2O3) as a passivation layer. Plasma free and low operation temperature with uniform coating of ALD technique leads to a conformal and defect free coverage on the side walls. This conformal coverage of rough surfaces also satisfies dangling bonds more efficiently while eliminating metal oxides in a self cleaning process of the A...
Indium rich InGaN solar cells grown by MOCVD
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This study focuses on both epitaxial growths of InxGa1-xN epilayers with graded In content, and the performance of solar cells structures grown on sapphire substrate by using metal organic chemical vapor deposition. The high resolution X-ray and Hall Effect characterization were carried out after epitaxial InGaN solar cell structures growth. The In content of the graded InGaN layer was calculated from the X-ray reciprocal space mapping measurements. Indium contents of the graded InGaN epilayers change from ...
Citation Formats
Y. Ergunt et al., “CdZnTe BULK-CRYSTAL GROWTH AND SURFACE PROCESSING TECHNOLOGY AT METU-CGL,” 2020, Accessed: 00, 2020. [Online]. Available: