Positron lifetime spectroscopy of defect structures in Cd_1–x Zn _x Te mixed crystals grown by vertical Bridgman–Stockbarger method

Abstract

Positron annihilation lifetime spectroscopy was used to examine grown-in defects in Cd1–x Zn x Te mixed crystals as a function of Zn content (x = 0, 0.07, 0.11, 0.49, 0.9, 0.95, 1) and measuring temperature. All samples were prepared using the high-pressure modified vertical Bridgman–Stockbarger method. The crystal structure and material phase were characterized by X-ray diffraction. The positron lifetime spectra reveal the presence of both open volumes and shallow traps regardless of the sample composition. In particular, both average and bulk lifetimes are found to be much higher in ternary alloys (CdZnTe) than those in binary systems (CdTe and ZnTe). This originates from distinct differences in average electron densities and the nature of open-volume defects between binary and ternary samples. Competition in positron trapping with increasing Zn content is observed between defects characteristic for both structural systems. Moreover, a clear correlation is shown between defects and the lattice thermal conductivity of studied samples. The applicability of the positron trapping model to CdTe-based materials is discussed.

Improving Proton Conductivity by Navigating Proton Trapping in High Scandium-Doped Barium Zirconate Electrolytes

“…We next expand the study of the proton trapping on hydrated Sc-doped BaZrO 3 and Y-doped BaZrO 3 . A better understanding of the nature of proton trapping as a function of doping level requires using special techniques such as nuclear magnetic resonance, , quasielastic neutron scattering, , or modeling and computational work. , PALS has been used to study the electron structure of ceramics and oxides on the nanoscale. ,− According to PALS theory, the positively charged positrons penetrate inside the bulk of the samples, thermalize, and diffuse until they annihilate with electrons , (Figure a). The presence of lattice dislocations or negatively charged defects affects positrons since they tend to be trapped in low electron density volumes .…”

Vibrational-mechanical properties of the highly-mismatched Cd1-xBexTe semiconductor alloy – Experiment and ab initio calculations

“…Cd 1-x Be x Te (𝑥=0, 0.03, 0.05, 0.07, 0.11) and Zn 1-x Be x Te (𝑥=0.04, 0.21) free-standing single crystals required for high-pressure (Raman scattering and / or X-ray diffraction) measurements are grown from the melt by mixing high-purity CdTe and ZnTe (99.9995, i.e., 5N quality) with Be (99.5, i.e., 2N quality) using the Bridgman method 54 . The Cd 1-x Be x Te composition is determined better than 1% by selective Cd and Be dosing via the inductively coupled plasma (ICP) method applied to powders.…”

Vibrational-mechanical properties of the highly-mismatched Cd1−xBexTe semiconductor alloy: experiment and ab initio calculations

“…Cd 1−x Be x Te ( , 0.03, 0.05, 0.07, 0.11) and Zn 1−x Be x Te ( , 0.21) free-standing single crystals required for high-pressure Raman and X-ray diffraction measurements are grown from the melt by mixing high-purity CdTe and ZnTe (99.9995, i.e., 5 N quality) with Be (99.5, i.e., 2 N quality) using the Bridgman method 56 . The Cd 1−x Be x Te composition is determined better than 1% by selective Cd and Be dosing via the inductively coupled plasma (ICP) method applied to powders.…”