In this study, effects of n-electrode patterns to the current spreading in the active region were analyzed on the blue
vertical light emitting diode (VLED) with GaN/InGaN multi quantum well (MQW). Several n-electrode patterns of the
VLED are designed, analyzed qualitatively, and investigated its effect to current spreading in the active region. A 3-dimensinal circuit model whose parameters are experimentally extracted from an actual VLED chip is adopted for the
quantitative analysis of current spreading. The n-electrode patterns are modeled and simulated by simple electrical
circuits in order to find the current distribution and current-voltage characteristics of devices. Based on theoretical
analysis results, blue VLEDs with different n-electrode patterns were fabricated and a series of measurements were
carried out. Analytic and experimental results for different n-electrode pattern showed quite similar tendencies. Finally,
we proposed some design methodologies for improved current spreading.
We investigated the dependency of waveguide structures on ripples of far-field patterns in 405nm GaN-based laser diodes theoretically and experimentally. As the n-type cladding layer thickness decreases, the passive waveguide modes strongly interact with an active layer mode. This suggests that the thicknesses of n-AlGaN/GaN superlattice clad and n-GaN waveguide layers have significant influences on FFP ripples. We successfully obtained very smooth far-field patterns perpendicular to the junction plane by optimizing both n-AlGaN/GaN clad layer thickness and n-GaN waveguide layer thickness.