Abstract. The first successful results of multifractal analysis application to a quantitative description of mosaic structure peculiarities, which are typical of GaN epitaxial layer with hexagonal modification grown on (0001) sapphire substrates, have been obtained. Characteristic size of the mosaic structure has been measured to be 200-800 nm. The direct dependence of mobility on the multifractal parameters (the Renyi dimension and the degree of the order index) of the surface topology of the mosaic structure has been observed for all GaN layers investigated.
The degradation of blue light emitting diodes (LEDs) with different structural disorder based on MQW InGaN/GaN grown by MOCVD on sapphire has been investigated. New approach to analyze the degradation has been used. It takes into account the structural disorder determined by the extended defect system relaxation and related with poor coalescence of the mosaic structure domains. The results obtained leads to assumption that the migration and segregations of Ga on domain dislocation boundaries of the mosaic structure and the change of energy activation of Mg related centers are important reasons of degradation for all types of LEDs The fastest degradation for poor ordered LEDs was observed.
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