AFM CHARACTERIZATION OF RAMAN LASER INDUCED DAMAGE ON CDZNTECRYSTAL SURFACES

Journal Article · Tue Oct 07 04:00:00 EDT 2008 · Journal of Electronic Materials

OSTI ID:972263

Teague, L; Duff, M

High quality CdZnTe (or CZT) crystals have the potential for use in room temperature gamma-ray and X-ray spectrometers. Over the last decade, the methods for growing high quality CZT have improved the quality of the produced crystals however there are material features that can influence the performance of these materials as radiation detectors. The presence of structural heterogeneities within the crystals, such as twinning, pipes, grain boundaries (polycrystallinity), and secondary phases (SPs) can have an impact on the detector performance. There is considerable need for reliable and reproducible characterization methods for the measurement of crystal quality. With improvements in material characterization and synthesis, these crystals may become suitable for widespread use in gamma radiation detection. Characterization techniques currently utilized to test for quality and/or to predict performance of the crystal as a gamma-ray detector include infrared (IR) transmission imaging, synchrotron X-ray topography, photoluminescence spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM) and Raman spectroscopy. In some cases, damage caused by characterization methods can have deleterious effects on the crystal performance. The availability of non-destructive analysis techniques is essential to validate a crystal's quality and its ability to be used for either qualitative or quantitative gamma-ray or X-ray detection. The work presented herein discusses the damage that occurs during characterization of the CZT surface by a laser during Raman spectroscopy, even at minimal laser powers. Previous Raman studies have shown that the localized annealing from tightly focused, low powered lasers results in areas of higher Te concentration on the CZT surface. This type of laser damage on the surface resulted in decreased detector performance which was most likely due to increased leakage current caused by areas of higher Te concentration. In this study, AFM was used to characterize the extent of damage to the CZT crystal surface following exposure to a Raman laser. AFM data reveal localized surface damage and increased conductivity in the areas exposed to the Raman laser beam.

• Research Organization: SRS
• Sponsoring Organization: DOE
• DOE Contract Number: AC09-08SR22470
• OSTI ID: 972263
• Report Number(s): SRNS-STI-2008-00149
• Journal Information: Journal of Electronic Materials, Journal Name: Journal of Electronic Materials; ISSN JECMA5; ISSN 0361-5235
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ANNEALING
ATOMIC FORCE MICROSCOPY
DETECTION
GAMMA RADIATION
GRAIN BOUNDARIES
LASERS
LEAKAGE CURRENT
NONDESTRUCTIVE ANALYSIS
PHOTOLUMINESCENCE
RADIATION DETECTORS
RAMAN SPECTROSCOPY
SPECTROSCOPY
SYNCHROTRONS
SYNTHESIS
TOPOGRAPHY
TRANSMISSION ELECTRON MICROSCOPY
TWINNING
X-RAY DETECTION
X-RAY SPECTROMETERS