Browsing by Author "Regassa, Asamin"

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    Investigation of Thermoluminescence from Amorphous Silicon Quantum Dots Using the Interactive Multiple Trap System Model
    (Addis Ababa University, 2018-12-04) Regassa, Asamin; Mesfin, Belayneh (PhD)
    The investigation of the effect of size variation on intensity of thermoluminescence emission from spherical amorphous silicon quantum dots using the model of interactive multi traps system (IMTS) model were studied in this work. The IMTS model consists of one active electron trap (AT), one thermally disconnected deep trap (TDDT), and one recombination centre (RC). Numerical simulations are carried out for quantum dots of diameters 3, 4, 5 , 6 nm to determine TL glow curve and relevant important kinetic parametres. We find that as the size of the Silicon QDs decreases, the intensity of thermoluminescence signal increase, the peak temperatures for each quantum dots is almost remains independent of the size of dots and the TL glow curve looks like first order kinetics. Also, by employing one-trap-one recombination centre (OTOR) model, we showed that the glow peaks of the quantum dots shift towards high temperature values, the widths of the glow curves gets broader and broader with an increase of the dots while the glow curves seems to obey second order kinetics. Furthermore, as the temperature increase; the concentration of electrons n(T) in the AT decreases, the concentration of electrons in the TDDT m(T) increases, and as the quantum dot size increase, concentrations of electrons nc(T) also increase. In addition the symmetry factor (μg), activation energy (E) the order of kinetics (b) as well as the instantaneous concentration of carriers in the traps and recombination centre are numerically simulated. The results obtained may be used while fabricating dielectric compounds enriched in silicon contents for TL applications. Furthermore, it may motivate further theoretical and experimental investigations of the study of the TL phenomena in silicon quantum dots.