Thermoluminescence kinetics of oxygen-related centers in AlN single crystals

Excitation and emission spectra of thermoluminescence (TL) in bulk aluminum nitride single crystals irradiated by UV have been studied. TL has been found to be most effectively excited by the 5.04 eV photons. The 3.44 eV band caused by recombination processes with oxygen–vacancy (V_Al − O_N)-centers dominates in the TL spectrum. Besides, the 2.91 and 2.0 eV emissions have been also observed. The TL mechanisms have been quantitatively analyzed in terms of formal kinetics of general order. On the basis of the obtained values and from their comparison with literature data it has been concluded that the main traps of charge carriers, responsible for the TL peak at 470 К, are formed by the VN vacancy. To interpret the observed regularities, the model of TL has been proposed, which satisfactorily agrees with independent data for thermally and optically stimulated processes in aluminum nitride.

Highlights

► 3D plots of thermoluminescence emission and excitation spectra in bulk AlN under UV.

► Comprehensive analysis of glow curves in terms of formal general order kinetics.

► We propose the band model of TL processes with VN-traps and (V_Al–O_N)-complexes.

Source: Diamond and Related Materials

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Three-dimensional analysis of dislocation multiplication in single-crystal silicon under accurate control of cooling history of temperature

Dislocation multiplication in single-crystal silicon during heating and cooling processes was studied by three-dimensional simulation under accurate control of the temperature history. Three different cooling temperature histories were designed. The results showed that the cooling rate in the high-temperature region has a large effect on the final dislocations and residual stress. The most effective method to reduce dislocations is to use a slow cooling rate in the high-temperature region.

Highlights

• 3D simulation of dislocation multiplication in single-crystal silicon was studied.

• Accurate control of temperature history in furnace was numerically implemented.

• Cooling rate in high-temperature region affects dislocations and residual stress.

• Slow cooling in high-temperature region is the best choice.

Source:Journal of Crystal Growth

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