Molybdenum News Center

GaN-Based Light-Emitting Diodes on Micro-Lens Patterned Sapphire Substrate

GaN-based light-emitting diodes (LEDs) were fabricated on a micro-lens patterned sapphire substrate (ML-PSS). ML patterning on the sapphire substrate was carried out by using photolithography with photo-resist reflow technique and dry etching process using chlorine based inductively coupled plasma. The ML-PSS was prepared using a periodic ML pattern with diameters of 3 μm and spacing of 2, 4, and 5 μm, respectively, on the c-plane sapphire substrate. The leakage current of the LEDs fabricated on the ML-PSS greatly decreased compared to that of a conventional LED and it decreases with increasing ML-pattern spacing; it decreases from 1.8 to 0.2 μA at reverse voltage of 15 V as the ML-pattern spacing is increased from 2 to 5 μm. The output power of the LED with 5 μm spacing was about 155% higher than that of a conventional LED and about 10% higher than that of the LED on the PSS with spacing of 2 μm. This improvement of the output power is contributed not only by reduction of dislocation density depending on spacing of patterning but also by the enhancement of light extraction efficiency with outcoupling via the ML patterned facets on sapphire substrate.

It describes the improved output power of GaN-based light-emitting diodes (LEDs) formed on a nanopatterned sapphire substrate (NPSS) prepared through etching with a self-assembled monolayer of 750-nm-diameter SiO2 nanospheres used as the mask. The output power of NPSS LEDs was 76% greater than that of LEDs on a flat sapphire substrate. Three-dimensional finite-difference time-domain calculation predicted a 40% enhancement in light extraction efficiency of NPSS LEDs. In addition, the reduction of full widths at half maximum in the ω-scan rocking curves for the planes of GaN on NPSS suggested improved crystal quality.


More molybdenum product: http://www.molybdenum.com.cn
Tel: 0592-5129696 Fax：0592-5129797
E-mail:  This email address is being protected from spambots. You need JavaScript enabled to view it.
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Tungsten News & Tungsten Price: http://www.chinatungsten.com

• < Prev
• Next >