Provided is a light emitting diode (LED) manufactured by using a wafer bonding method and a method of manufacturing a LED by using a wafer bonding method. The wafer bonding method may include interposing a stress relaxation layer (33) formed of a metal between a semiconductor layer (20) and a bonding substrate (31). When the stress relaxation layer is used, stress between the bonding substrate and a growth substrate may be offset due to the flexibility of metal, and accordingly, bending or warpage of the bonding substrate may be reduced or prevented.

Light-emitting device and method of manufacturing the same

Transparent conducting oxides for electrode applications in light emitting and absorbing devices

Staggered InGaN quantum wells (QWs) grown by metal-organic chemical vapor deposition are demonstrated as improved active region for visible light emitters. Theoretical studies indicate that InGaN QW with step-function-like In content in the quantum well offers significantly improved radiative recombination rate and optical gain in comparison to the conventional type-I InGaN QW. Experimental results of light emitting diode (LED) structure utilizing staggered InGaN QW show good agreement with theory. Polarization band engineering via staggered InGaN quantum well allows enhancement of radiative recombination rate, leading to the improvement of photoluminescence intensity and LED output power.

Polarization engineering via staggered InGaN quantum wells for radiative efficiency enhancement of light emitting diodes

Enhancement of light extraction from light emitting diodes

GaN-based light-emitting diodes (LEDs) with emitting wavelength of 450 nm were grown on patterned sapphire substrates (PSSs) fabricated by chemical wet etching The crystallography-etched facet was {1-102} R-plane with a 57deg against {0001} C-axis and had superior capability for enhancing light extraction efficiency The light output power of the PSS LED was 115 times higher than that of the conventional LED at an injection current of 20 mA The output power and external quantum efficiency were estimated to be 9 mW and 164%, respectively The improvement was attributed not only to geometrical shapes of {1-102} crystallography-etched facets that efficiently scatter the guided light to find escape cones, but also to dislocation density reduction by adopting the PSS growth scheme

https://ir.nctu.edu.tw:443/bitstream/11536/12320/1/000238708300052.pdf

Enhancing the output power of GaN-based LEDs grown on wet-etched patterned sapphire substrates

Near-ultraviolet nitride-based light-emitting diodes (LEDs) with peak emission wavelengths around 410 nm were fabricated onto c-face patterned sapphire substrates (PSS). It was found that the electroluminescence intensity of the PSS LED shown 63% larger than that of the conventional LED. For a typical lamp-form PSS LED operating at a forward current of 20 mA, the output power and external quantum efficiency were estimated to be 10.4 mW and 14.1%, respectively. The improvement in the light intensity could be attributed to the decrease of threading dislocations and the increase of light extraction efficiency in the horizontal direction using a PSS.

Enhanced output power of near-ultraviolet InGaN-GaN LEDs grown on patterned sapphire substrates

Enhanced Output Power of Near-Ultraviolet InGaN-GaN LEDs Grown on Patterned

There is a significant gap between the internal and external efficiencies of conventional GaN light-emitting diodes (LEDs). The reason for this shortfall is the narrow escape cone for light in high refractive index semiconductors. In this letter, the p-side-up GaN∕sapphire LEDs with surface textured indium tin oxide (ITO) widow layers were investigated using natural lithography with polystyrene spheres as the etching mask. Under optimum etching conditions, the surface roughness of the ITO film can reach 140 nm while the polystyrene sphere on the textured ITO surface is maintained at about 250–300 nm in diameter. The output power of the ITO∕GaN LED with and without surface texturing is 10.9, and 8.5 mW at 20 mA, respectively. The LEDs fabricated using the surface-textured ITO produced an output power that exceeded that of the planar-surface LED by about 28% at 20 mA.

GaN-based light-emitting diodes with indium tin oxide texturing window layers using natural lithography

A large-area (1 /spl times/ 1 mm) vertical conductive GaN-mirror-Cu light-emitting diode (LED) fabricated using the laser liftoff and electroplating techniques is demonstrated. Selective p-GaN top area was first electroplated by the thick copper film, and then an excimer laser was employed to separate the GaN thin film from the sapphire substrate. The luminance intensity of the vertical conductive p-side-down GaN-mirror-Cu LED presented about 2.7 times in magnitude as compared with that of the original GaN-sapphire LED (at 20 mA). The light output power for the GaN-mirror-Cu LED was about twofold stronger (at 500 mA). A more stable peak wavelength shift under high current injection was also observed.

High-power GaN-mirror-Cu light-emitting diodes for vertical current injection using laser liftoff and electroplating techniques

A high-power chip structure of GaN/mirror/Cu light-emitting diodes (LEDs) was developed by a combination of laser lift-off and electroplating techniques. Especially, the LED samples can be accomplished without additional scribing or dicing process. The luminance intensity of the GaN/mirror/Cu LED is about 50% higher than that of the original GaN/sapphire sample. The output power of the GaN/mirror/Cu LED increases linearly with injection current up to 180 mA, while early saturation of the GaN/sapphire device occurs at 70 mA. These indicate that the joule heating is less pronounced for the GaN/mirror/Cu LED sample where the metallic substrate provides a good heat sink.

C. E. Lee

Papers

Enhanced output power of near-ultraviolet InGaN-GaN LEDs grown on patterned sapphire substrates

Enhanced Output Power of Near-Ultraviolet InGaN-GaN LEDs Grown on Patterned

GaN-based light-emitting diodes with indium tin oxide texturing window layers using natural lithography

High-power GaN-mirror-Cu light-emitting diodes for vertical current injection using laser liftoff and electroplating techniques

High-power GaN light-emitting diodes with patterned copper substrates by electroplating