Estimation of thermoluminescence kinetic parameters in h-BN by different techniques

Abstract

Particulars of the UV-irradiated h-BN micropowder were studied by the means of spectrally resolved thermoluminescence (TL) technique. Using curve fitting, peak shape, various heating rates and initial rise methods an estimation of kinetic parameters (activation energy, effective frequency factor and kinetics order) for the active capture centers, forming the complex multitrap system, was performed. It is shown that TL in 380 and 425 nm bands is caused by the radiative transitions of electrons from 1B- and 3B-centers levels with 0.7 and 1.2 eV energy below the bottom of conduction band to the carbon levels (CN-centers) with the activation energy of 1.4 eV above the top of valence band, respectively. The consideration of temperature quenching of luminescence in the evaluation of traps activation energy is analyzed. It is found that, under the thermal activation of electron (1B- and 3B-centers) and hole (CN- centers) traps, the TL processes of first and second kinetics order dominate respectively. A mechanism of electron tunneling from the deep traps to 1B- and 3B-centers in h-BN following the registered TL processes is being discussed. An energy-level diagram describing the thermally stimulated mechanisms of charge carriers redistribution was proposed for the UV-irradiated h-BN.