High performance thin-film flip-chip InGaN–GaN light-emitting diodes

Abstract

Data are presented on the operation of thin-film flip-chip InGaN∕GaN multiple-quantum-well light-emitting diodes (LEDs). The combination of thin-film LED concept with flip-chip technology is shown to provide surface brightness and flux output advantages over conventional flip-chip and vertical-injection thin-film LEDs. Performance characteristics of blue, white, and green thin-film flip-chip 1×1mm2 LEDs are described. Blue (∼441nm) thin-film flip-chip LEDs are demonstrated with radiance of 191mW∕mm2sr at 1A drive, more than two times brighter than conventional flip-chip LEDs. An encapsulated thin-film flip-chip blue LED lamp is shown to have external quantum efficiency of 38% at forward current of 350mA. A white lamp based on a YAG:Ce phosphor coated device exhibits luminous efficacy of 60lm∕W at 350mA with peak efficiency of 96lm∕W at 20mA and luminance of 38Mcd∕m2 at 1A drive current. Green (∼517nm) devices exhibit luminance of 37Mcd∕m2 at 1A.