Optoelectronic Properties of GaN-Based Light-Emitting Diodes with Different Mesa Structures

Abstract

GaN/InGaN lighting-emitting diodes with different mesa structures are studied. The current-voltage characteristics, light output power, luminous efficiency, and peak wavelength of the GaN/InGaN lighting-emitting diodes with different mesa patterns are compared. It shows that the current-voltage characteristics of the chips with more mesa areas are im- proved greatly by reducing the current crowding. With higher injection current the light output powers of GaN-based LED with more mesa areas are enhanced. And the chips with more P-electrode area have a smaller red shift and a little bit blue shift due to the reduction of the current crowding

Experimental and Modeling Investigations of Miniaturization in InGaN/GaN Light-Emitting Diodes and Performance Enhancement by Micro-Wall Architecture

“…All LED chips are fabricated within a 2 mm × 2 mm region on the same epitaxial wafer to avoid the spatial inhomogeneity in the wafer with standard fabrication procedures in order to eliminate the influence by crystalline quality, epitaxial growth, and fabrication processes, which is the possible reason for the discrepancy in the conclusion of the size-reduction effect among the previous reports ( Tao et al, 2012 ; Olivier et al, 2017 ; Singh et al, 2017 ; Daami et al, 2018 ). The p-contact metal totally covers the top surface of the p-GaN layer to avoid the influence of the electrode pattern, which is different from the previous works ( Song, 2012 ; Singh et al, 2017 ). The experimentally measured optical output power as a function of current density for LEDs with different mesa dimensions are illustrated in Figure 3A , from which we can see that the optical output power increases consistently with the mesa size narrowed from 180 to 45 μm in the y -direction.…”

“…It is worth noting that if the finger shape or other types of electrode pattern is adopted in the p-contact metal layer, the electrode distribution along the lateral directions (both x - and y -directions) will further affect the current spreading performance. In that case, the current spreading is subjected to the coupling effect of size-reduction in the x- direction and electrode patterns ( Guo and Schubert, 2001 ; Song, 2012 ).…”