Stimulated luminescence emission from localized recombination in randomly distributed defects

• Published in: Journal of physics. Condensed matter Vol. 24; no. 38; p. 385402
• Main Authors: Jain, Mayank, Guralnik, Benny, Andersen, Martin Thalbitzer
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 26.09.2012; Institute of Physics
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Other luminescence and radiative recombination; Physics; Stimulated emission; Thermoluminescence; Complex defect; Acceptor donor pair; Stimulated emission; Charge carrier recombination; Tunnel effect; Analytical method; Random distribution; Excited states; Power law; Thermoluminescence
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/24/38/385402

We present a new kinetic model describing localized electronic recombination through the excited state of the donor (d) to an acceptor (a) centre in luminescent materials. In contrast to the existing models based on the localized transition model (LTM) of Halperin and Braner (1960 Phys. Rev. 117 408-15) which assumes a fixed d → a tunnelling probability for the entire crystal, our model is based on nearest-neighbour recombination within randomly distributed centres. Such a random distribution can occur through the entire volume or within the defect complexes of the dosimeter, and implies that the tunnelling probability varies with the donor-acceptor (d-a) separation distance. We first develop an 'exact kinetic model' that incorporates this variation in tunnelling probabilities, and evolves both in spatial as well as temporal domains. We then develop a simplified one-dimensional, semi-analytical model that evolves only in the temporal domain. An excellent agreement is observed between thermally and optically stimulated luminescence (TL and OSL) results produced from the two models. In comparison to the first-order kinetic behaviour of the LTM of Halperin and Braner (1960 Phys. Rev. 117 408-15), our model results in a highly asymmetric TL peak; this peak can be understood to derive from a continuum of several first-order TL peaks. Our model also shows an extended power law behaviour for OSL (or prompt luminescence), which is expected from localized recombination mechanisms in materials with random distribution of centres.