Analysis with a multilayer model of heating rate effect on thermally stimulated luminescence, conductivity and exoelectronic emission of alpha -Al sub 2 O sub 3

A theoretical model destined to analyse simultaneously thermally stimulated luminescence (TL), conductivity (TSC) and exoelectronic emission (TSEE) measurements is developed and applied to alpha -Al sub 2 O sub 3 material. In the scope to distinguish between bulk processes, for TL and TSC, and surface emission for TSEE, a multilayer model is adopted. It is also assumed that TSEE results from thermionic mechanism. The model allows the study of heating rate effect on TL, TSC and TSEE responses. It is experimentally established that response of approx =450 K TL peak decreases when heating rate increases. Simultaneously, TSC response remains constant whereas TSEE signal increases. The attenuation of TL response is explained by thermal quenching of F-centre luminescence and it is well described by the Mott-Seitz theory.