High Performance Thin-Film Flip-Chip InGaN–GaN Light-Emitting Diodes

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 1×1 mm2 LEDs are described. Blue (∼441 nm) thin-film flip-chip LEDs are demonstrated with radiance of 191 mW/mm2 sr at 1 A 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 350 mA. A white lamp based on a YAG:Ce phosphor coated device exhibits luminous efficacy of 60 lm/W at 350 mA with peak efficiency of 96 lm/W at 20 mA and luminance of 38 Mcd/m2 at 1 A drive current. Green (∼517 nm) devices exhibit luminance of 37 Mcd/m2 at 1 A.

We have measured polarized Raman spectra in a 2.0 mu m GaN epitaxial layer of high quality, grown on a sapphire substrate. All symmetry-allowed optical phonons in GaN have been assigned as follows: A1(LO), 735 cm-1; A1(TO), 533 cm-1; E1(LO), 743 cm-1; E1(TO), 561 cm-1; E2, 144 and 569 cm-1. Using the Lyddane-Sachs-Teller relation, the static dielectric constants of GaN for the ordinary and extraordinary directions have been estimated as epsilon perpendicular to 0=9.28 and E/sub //0/=10.1. We have also observed quasi-LO phonons in GaN. A brief discussion on these will be given.


Tungsten Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

• < Prev
• Next >