## Characteristics of the 1.1 eV Photoluminescence (PL) Band in CdZnTe
The 1.1 eV PL band in CdZnTe is commonly associated with radiative recombination involving deep-level defects, often linked to intrinsic vacancies, antisites, or complex defect centers within the bandgap. This band serves as a sensitive optical fingerprint of the defect population and their charge states, reflecting changes in the defect landscape under various external stimuli such as illumination and electric fields.
## Correlation Between 1.1 eV PL Band Intensity and Microhardness
Under illumination, the intensity and spectral features of the 1.1 eV PL band show distinct variations that closely correlate with changes in the microhardness of CdZnTe:
* PL Intensity Increase and Hardening: An increase in the 1.1 eV PL band intensity generally indicates enhanced radiative recombination from deep-level defects that have trapped carriers. This trapping correlates with increased charging of dislocation cores, which strengthens electrostatic pinning forces. As a result, dislocation mobility is hindered, leading to an increase in microhardness (hardening).
* PL Intensity Decrease and Softening: Conversely, a decrease in the PL intensity suggests reduced carrier trapping at these deep levels, possibly due to carrier neutralization or trap emptying. Reduced trap occupancy lowers dislocation core charging and weakens pinning, facilitating easier dislocation glide and thus softening of the material.
## Mechanistic Insights Linking PL Behavior to Mechanical Response
The 1.1 eV PL band reflects the dynamic occupancy of deep traps that serve as key players in modulating the electrostatic environment around dislocations:
* Carrier Trapping at Deep Levels: Trapped carriers at defect centers enhance localized charge accumulation, which manifests as stronger PL emission at 1.1 eV and simultaneously increases mechanical hardness via dislocation pinning.
* Carrier Neutralization and Recombination: When illumination conditions or bias cause detrapping or recombination, the defect states become less occupied, reducing PL emission and softening the crystal.
* Temporal Evolution: Changes in the 1.1 eV PL intensity during illumination correlate temporally with microhardness variations, indicating that both optical and mechanical properties respond to the same underlying defect charge dynamics.
## Summary
The behavior of the 1.1 eV PL band in CdZnTe under illumination is closely correlated with microhardness changes. Enhanced PL intensity at this band signifies increased carrier trapping at deep defect levels, which raises dislocation core charge and mechanical hardness. Conversely, diminished PL intensity corresponds to trap neutralization and mechanical softening. This correlation provides a direct optical probe into the defect-related mechanisms controlling the photo-plastic behavior of CdZnTe.
CdZnTe Association (CdZnTe.com)
https://www.cdznte.com/blog/how-does-the-behavior-of-the-1-1-ev-pl-band-in-cdznte-correlate-with-changes-in-microhardness-under-illumination.html
