Failure analysis of InGaN/GaN LEDs with emission wavelength between 440 nm and 550 nm

While longer wavelength emission from InGaN/GaN light-emitting diodes can be achieved by increasing the Indium (In) content in the qunatum wells, the increased In content gives rise to side-effects to the material and device performance and reliability. It was found that the induced strain in the wafer and the density of threading dislocations increases with increasing In content. From current-voltage and 1/f noise measurements, it was observed that the leakage currents, static resistance and noise magnitudes rises monotonically with increasing emission wavelength (In composition), which can be attributed to higher defect concentrations. After undergoing a 1000-hr reliability test, it was discovered that the optical degradation rates for the longer wavelength green LEDs were significantly higher than those of shorter wavelength. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim