The impact of 3D compositional fluctuations on the external quantum efficiency and defect generation in nitride alloys with a low In or Al molar fraction

Peculiarities of the low-frequency noise, the evolution of the full width at half maximum (FWHM) in electroluminescence spectra with the injection current change were studied in InGanN/GaN and AlGaN/GaN MQW containing less than 10% of In and Al components. It was shown that one of the reasons behind the low values of the external quantum efficiency in the LEDs based on these structures is 3D fluctuations in the alloy composition with the local regions of the irregular compound. The results of the investigation of the I-V characteristics and spectral noise density dependences in the LEDs after different aging stages are presented. The defect generation under the injection current during the degradation is shown to occur locally in the extended defects and in the regions of the irregular alloy composition. (paper)