Research and fabrication of high power LEDs with transparent electrodes

Abstract

In this paper we studied the influence of N electrode on the extraction efficiency of high power light-emitting diodes (LEDs). Simulation and experimental results show that comparing with traditional metal N electrodes the extraction efficiency of LEDs with transparent N electrode is increased by 15%, and it is easier in process than the other techniques. So we proposed a new kind of strip LEDs with transparent electrodes on both P-GaN and N-GaN. The design of transparent electrodes was trade-off between transmittance and resistance. At the same time, the strip structure has some advantages over the traditional square LEDs, which can increase the extraction efficiency and reduce the thermal resistance. Antireflective and high reflective optical coatings were also used in this design. The fabrication of LEDs with transparent electrodes on both P-GaN and N-GaN has been demonstrated. The output power of blue LEDs is 240mW at 350mA, forward voltage is below 3.5V. The luminous flux of white LEDs reached 65lm at 350mA.