CdZnTe is a high efficiency, room temperature radiation detection material that has attracted great interesting in medical and security applications. CZT crystals can be grown by various methods. Particularly, CZT grown with the Transfer Heater Method (THM) method have been shown to have fewer defects and greater material uniformity. In this work, we developed a proof-of-concept dual lighting NIR imaging system that can be implemented to quickly and nondestructively screen CZT boule and wafers during the manufacturing process. The system works by imaging the defects inside CZT at a shallow depth of focus, taking a stack of images step by step at different depths through the sample. The images are then processed with in-house software, which can locate the defects at different depths, construct the 3D mapping of the defects, and provide statistical defect information. This can help with screening materials for use in detector manufacturing at an early stage, which can significantly reduce the downstream cost of detector fabrication. This inspection method can also be used to help the manufacturer understand the cause of the defect formation and ultimately improve the manufacturing process.
[1]
Xavier Binefa,et al.
Three-dimensional inspection of integrated circuits: a depth from focus approach
,
1992,
Electronic Imaging.
[2]
Arnold Burger,et al.
Characterization of detector-grade CdZnTe crystals grown by traveling heater method (THM)
,
2010
.
[3]
I. J. Nakonechnyj,et al.
Extended Defects in CdZnTe Radiation Detectors
,
2009,
IEEE Transactions on Nuclear Science.
[4]
Ralph B. James,et al.
Structural and chemical analysis of grain boundaries and tellurium precipitates in commerical Cd1-xZnxTe
,
1998,
Optics + Photonics.