Advancements in Large CZT Crystal Growth via PBN Crucibles
Overcoming the Bottleneck: Enhancing Large-Size CZT Crystal Performance
Recently, a team of researchers from the Department of Materials Physics at the Autonomous University of Madrid, Spain, led by J. Crocco, A. Black, H. Bensalah, Q. Zheng, V. Carce´len, and E. Dieguez, published a paper titled "Investigation of crystal growth of 50 mm CZT using SiC pedestal and pBN crucible" in the Journal of Crystal Growth. The study aimed to improve the structural, optical, and electronic performance of large-size Cd0.9Zn0.1Te (CZT) crystals for producing high-quality nuclear imaging materials.
CZT is a highly promising semiconductor material with widespread applications in medical imaging, industrial detection, and national security. However, producing large-size, high-quality CZT crystals has been a significant challenge. The researchers employed the Vertical Gradient Freeze (VGF) method to grow CZT crystals in a five-zone furnace and used a novel crystal growth pedestal for real-time temperature gradient monitoring. Notably, the scientists chose pyrolytic boron nitride (PBN) as the crucible material for crystal growth, owing to its excellent thermal conductivity and chemical stability, making it an ideal container material.
The PBN Crucible: The Key to Crystal Growth
The article highlights that the geometric structure of the PBN crucible, particularly the conical-to-cylindrical transition region, significantly influences the heat flow and grain structure evolution during the crystal growth process. In the VGF growth process with PBN crucible, CZT crystals first solidify from the bottom of the crucible and then move upward until the entire charge is solidified. The researchers found that by combining the SiC (silicon carbide) pedestal with the geometric shape of the PBN crucible, they could increase the axial heat flow and reduce the radial heat flow, thereby improving the temperature gradient at the tip of the crucible. This helped to more effectively extract the latent heat during the initial stages of crystal growth, leading to higher-quality CZT materials.
Furthermore, the high thermal conductivity of the PBN crucible along the sidewall facilitates heat flow in the wall direction while suppressing radial heat losses perpendicular to the wall. This anisotropic thermal conduction characteristic also had a positive impact on the crystal growth kinetics.
The Synergistic Effect of the SiC Pedestal
The research team found that using the SiC pedestal further optimized the CZT crystal growth process. Compared to experiments without a pedestal, the use of the SiC pedestal increased the axial temperature gradient and axial heat flow in the early stages of crystal growth, influencing the crystal growth kinetics. Additionally, near the conical-to-cylindrical transition region of the PBN crucible, the researchers observed the nucleation and growth of new grains, which may be related to the impact of the crucible's geometric shape on heat transfer characteristics. The experiments with the SiC pedestal exhibited higher axial temperature gradients and axial heat flows at the start of crystal growth, contributing to improved crystal quality.
Characterization of the grown CZT crystals confirmed the positive impact of the SiC pedestal on the material's performance, laying a foundation for the future application of CZT in nuclear imaging and other fields.
PBN Crucibles Elevate Research Collaboration
QSAM inc, a leading manufacturer of PBN crucibles in the market, provides high-quality services to research users. Their professional manufacturing capabilities and customized services allow researchers to obtain the most suitable high-quality crucibles, supporting the in-depth advancement of scientific research.
PBN Crucible
This groundbreaking research not only provides new insights into large-size CZT crystal growth but also demonstrates the excellent performance of PBN crucibles in extreme environments. The anisotropic thermal conduction characteristics of PBN crucibles and their impact on crystal growth kinetics have provided researchers with better experimental conditions. In the future, PBN crucibles will continue to inject powerful momentum into scientific research, driving the birth of more innovative achievements. As this technology continues to evolve, high-quality CZT materials will undoubtedly bring new breakthroughs in medical imaging, industrial detection, and national security applications.