Stimulated luminescence emission from localized recombination in randomly distributed defects

Area of Science:

• Solid State Physics
• Materials Science
• Luminescence

Background:

• Existing models for electronic recombination in luminescent materials often assume fixed tunneling probabilities.
• The localized transition model (LTM) by Halperin and Braner (1960) is a prominent example, but it simplifies the complex reality of randomly distributed centers.

Purpose of the Study:

• To develop a new kinetic model for localized electronic recombination that accounts for varying donor-acceptor separation distances.
• To provide a more accurate description of thermally stimulated luminescence (TL) and optically stimulated luminescence (OSL) phenomena in materials with randomly distributed centers.

Main Methods:

• Development of an 'exact kinetic model' incorporating spatial and temporal dynamics of recombination.
• Creation of a simplified one-dimensional, semi-analytical model focusing on temporal evolution.
• Comparison of model predictions with established theoretical frameworks and experimental observations.

Main Results:

• Excellent agreement between the exact and simplified models for TL and OSL predictions.
• The new model predicts highly asymmetric TL peaks, contrasting with the first-order kinetics of the LTM.
• The model demonstrates extended power law behavior for OSL, consistent with localized recombination in disordered systems.

Conclusions:

• The proposed kinetic model offers a more realistic description of localized electronic recombination in luminescent materials with random center distributions.
• The model's ability to predict asymmetric TL peaks and extended OSL power laws enhances understanding of luminescence mechanisms.
• This work provides a valuable tool for analyzing and predicting the luminescence properties of various materials.