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Keywords:

  • GaN;
  • light-emitting diode;
  • ray tracing;
  • r-plane patterned sapphire substrate;
  • semipolar;
  • (11–22)

Abstract

We have succeeded in the growth of a high-quality semipolar (11–22) GaN layer on an r-plane patterned sapphire substrate (r-PSS). In this study, we report on green-light-emitting diodes (LEDs) fabricated on the (11–22) GaN layer on the r-PSS. The optical property of (11–22) MQWs on the r-PSS improved from that of the same MQWs on an m-plane sapphire substrate. The green light emission from the LED on the r-PSS was confirmed, which exhibited scattered light emission. The effect of the r-PSS on the improvement of light extraction was evaluated by ray tracing simulation, which is higher than that of a conventional LED on a c-PSS. This improvement is derived from the air void structure in the LED fabricated on the r-PSS. It was also confirmed that the LED had a small blue shift compared with that on the conventional green LED, and that the quantum confined Stark effect can be reduced using the semipolar (11–22) GaN layer on the r-PSS.