Optimization of electrode structure for flip‐chip HVLED via two‐level metallization

In this article, we demonstrated an optimized electrode structure for high voltage LED (HVLED) using a two-level metallization technique. The first-level metallization is to form interdigitated p and n electrodes with narrow metal fingers. After passivation, a second-level reflective metallization was deposited to form a continuous reflector. Comparing the performance of HVLEDs with bar shape electrode, square shape electrode, and n finger interposed electrode, the HVLEDs with interdigitated p and n finger electrodes show better current uniformity, higher light output power (LOP) and larger wall plug efficiency (WPE). The LOP of such single HVLED chip with 8 sub LED cells on pattern sapphire substrate sample reaches 500 mW at 100 mA current injection. Using flip-chip bonding technique to connect four such chips serially, LOP can reach 2 W at 100 mA drive current. The high brightness HVLED with optimized electrodes enables flexible driver designs for solid state lighting and other applications.

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