High-Efficiency InGaAlP Visible Light-Emitting Diodes

Abstract

A new structure for InGaAlP light-emitting diodes (LEDs) which include a GaAlAs current-spreading layer has been designed. Remarkable improvements in external efficiency have been achieved using this structure. The photoluminescence and electroluminescence characteristics of high-Al-content InGaAlP alloys have been investigated. A GaAs substrate with an intentional surface misorientation from the nominally (100) plane towards the [011] direction was found to have a marked effect on the improvement of emission properties. The external quantum efficiency was 1.2% at 592 nm for an In 0.5 (Ga 0.7 Al 0.3 ) 0.5 P active layer LED. These LEDs have been operated for more than 1500 hours at 80°C and 50 mA.