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

Abstract

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.

High-Speed Visible Light Communication Based on a III-Nitride Series-Biased Micro-LED Array

“…The series-biased LED arrays, which feature a monolithically-integrated configuration of multiple series-connected LED junctions, are considered to be reliable, compact and inexpensive light sources [14], [15], [16], [17], [18]. Compared with conventional broad-area LEDs, while retaining high optical power output, these LED arrays normally have a higher turnon voltage and lower driving current under direct-current (DC) operation.…”

Improving the −3 dB bandwidth of medium power GaN-based LEDs through periodic micro via-holes for visible light communications

“…One big hole in the LED might release more growth stresses inside the epitaxy layers than periodic small via-holes, thus the blue shift may partly 7 be resulted from the quantum-confined stark effect (QCSE) [17,18]. But the periodic small via-holes will generate more uniform stress and current distributions in the active region than only one big hole, it is expected that the internal quantum efficiency of the LED can be improved by periodic small via-holes [11][12][13][14]. inside the LED, which can explain why the sample LED exhibits a wider FWHM than the control LED.…”

“…For power-type LEDs, the poor current spreading and the resulted severe current-crowding always damaged their optical-electrical performances. Optimizing the LED chip design through special n-contact electrodes had been reported to improve the current spreading [11][12][13][14]. Lv by the current-spreading structure and the gold wire connection.…”

High power InGaN/GaN flip-chip LEDs with via-hole-based two-level metallization electrodes

“…Geometric topology of electrodes has been reported to have much impact on current spreading and subsequent optoelectronic characteristics. An optimized electrode pattern enables uniform current spreading and higher utilization ratio of light emitting area . Besides, in flip‐chip technology, fabrication of p‐type contact with high reflectivity is of significant importance .…”