Highly efficient broad‐area blue and white light‐emitting diodes on bulk GaN substrates

Abstract

Highly efficient light emitting diodes (LEDs) with peak emission wavelengths of nominally 450 nm were grown, fabricated and tested. The growth was performed by metal organic chemical vapour deposition. The LEDs were grown on c ‐plane (0001) bulk GaN substrates and fabricated into broad‐area devices with active area 0.01 cm2. Considerations were made to improve extraction efficiency, including transparent contacts, suspended mirror‐less packaging and encapsulation in a truncated pyramid optic. These factors resulted in LEDs with high peak external quantum efficiency and reduced efficiency droop. The output power and external quantum efficiency at 20 mA were 38.5 mW and 68.9%. At 100 mA, they were 170 mW and 60.9%. White LEDs were fabricated by application of a yellow phosphor to the blue LEDs. The white LED luminous flux and efficacy at 20 mA was 9.6 lm and 128 lm/W. The chromaticity coordinates and correlated colour temperature were (0.348 K, 0.378 K) and 4998 K. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Method for modulating the wafer bow of free-standing GaN substrates via inductively coupled plasma etching

“…Furthermore, vertical devices could be grown on electrically conductive GaN substrates to reduce current crowding and self-heating effects of devices. Free-standing GaN substrates have been widely used in laser diodes (LDs) [2] and high-power light emitting diodes (LEDs) [3] owing to its low dislocation density and superior thermal electrical properties. Currently, free-standing GaN substrates can be successfully obtained by growing thick GaN film hetero-epitaxially on a foreign base substrate in hydride vapor phase epitaxy (HVPE), and subsequently separating from the original substrate using laser lift-off (LLO) [4], chemical lift-off [5], and self-separation [6].…”

Diffusion injected multi-quantum well light-emitting diode structure

“…[http://dx.doi.org/10.1063/1.4866343] Light-emitting diode (LED) structures based on nanowires, [1][2][3][4][5][6] surface plasmon coupled LEDs, 7-10 and largearea high-power LEDs 11 have recently received increasing amount of attention as a potential way to increase the output power and efficiency of LEDs. Typically, in each of these LED structures, current transport is enabled by conventional configuration where the active region, e.g., quantum well (QW) or multi-quantum well (MQW) stack, is sandwiched between p-and n-doped regions.…”

Homoepitaxy on GaN substrate with various treatments by metalorganic vapor phase epitaxy

“…GaN substrates have great potential in the manufacturing of laser diodes (LD) [1] and high-power light emitting diodes (LEDs) [2] owing to their low dislocation density and superior thermal electrical properties. Currently, GaN substrates are formed by several methods, such as hydride vapor phase epitaxy (HVPE) [3], Na-flux method [4], and ammonothermal method [5].…”