An investigation was made of dislocations in GaN-based laser diodes on epitaxial lateral overgrown GaN layers by using transmission electron microscopy and cathodoluminescence microscopy and found a correlation between dislocations and device reliability. Dislocation density in the seed regions of epitaxial lateral overgrown GaN layers was of the order of 108/cm2, while that in the wing regions was less than mid-106/cm2. The origin of dislocations in the wing regions was the extension of defects in highly defective regions near to the GaN layer/substrate interface in the seed regions. The lifetime of laser diodes had a strong correlation with consumption power. However, some laser diodes had a shorter lifetime although their consumption power was almost the same. In the laser diodes with short lifetimes, dislocations lying in the c-plane were formed below the active regions, bent towards the c-axis and threaded upwards to active regions. These newly created dislocations could become detrimental to the device lifetime.

Dislocations in GaN-Based Laser Diodes on Epitaxial Lateral Overgrown GaN Layers. S.Tomiya, H.Nakajima, K.Funato, T.Miyajima, K.Kobayashi, T.Hino, S.Kijima, T.Asano, M.Ikeda: Physica Status Solidi A, 2001, 188[1], 69-72