Kyselyuk M. Acoustic emission nondestructive control of degradation processes of the InGaN/GaN light - emitting diodes

Dissertation is devoted to acoustic-emission non-destructive control of degradation processes of the In1-хGaхN/GaN light - emitting diodes. Based on the acoustic emission method the method of step-by-step increase of the current loading of the light - emitting structures is developed, which is cause minimal transformations in the system of the extended defects - due to activating of internal thermo-mechanical strains induced by the current and caused internal deformations of transfer of point defects. It is proposed the model of AE sources of nano-sized semiconductor light - emitting structure at flowing of direct current within the framework of which, correlation of AE signals and fluctuations and degradation of quantum yield is caused by the origin, accumulation and relaxation of internal thermo-mechanical strains. Here the AE active source is an indium enriched element. The method of determination of location of AE active sources of the InGaN/GaN/Al2O3 of the light - emitting structures is developed on a flash or fading of electroluminescence. The method of the non-active testing of light-emitting diodes and model of device, which will realize this method of verification in the devices of enhanceable responsibility, is developed. The basic advantage of method is absence of luminescence of tested elements at verification. It's realized by testing of two points of current-voltage characteristic, for which is insufficient energy for excitation of interband transitions. Revealed the reason, kind and mechanism of breakdown, as a result of the forced regimes (functioning at own warming-up conditions) of the industrial light-emitting diodes, produced due to planar technology in the polymer package. Depending on the loading value found out such breakdown kind: degradation of light-emitting structure (as a result of generation, accumulation and transfer of the linear defects), tearing away of the whiskers from a contact microball, caused by the thermo-cycled and linear expansion of light - emitting structure, change of radiation type from electroluminescence on a gas- discharge (at achievement of temperature of non oxidation thermodestruction of the polymer package), that is important at reliability prognostication of LED matrices.