Improved Light Extraction Efficiency by Photonic Crystal Arrays on Transparent Contact Layer Using Focused Ion Beams

Wu, G.M.; Tsai, Bor-Chen; Kung, Shu-Yen; Wu, Congyi

doi:10.12693/aphyspola.120.140

Cited by 4 publications

(3 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The most common structures are nano-sized air holes in dielectric slabs and also dielectric nano-rods surrounded by lower dielectric media such as air. In the last decade, this new class of crystal structures has attracted engineering interest owing to their capabilities in controlling light emission and the propagation of light waves [3]. Wu et al proposed a compact optical switch for self-collimated light beams in a liquid-crystal-modulated photonic crystal [4].…”

Section: Introduction *mentioning

confidence: 99%

Study of Two-Dimensional Photonic Crystal Arrays for Beam Splitters

Wu¹,

Ju²,

Chang³

et al. 2016

View full text Add to dashboard Cite

The effects of periodic modulation in dielectric constants on the formation of photonic band gaps of two-dimensional arrays have been characterized. When a defect is introduced into a perfect photonic crystal, a localized effect may be found at frequencies within the photonic band gap. A line defect thus acts as a waveguide, and a point defect can behave as a resonant cavity. In this report, we investigated photonic crystal structures based on germanium (n = 4.0), silicon (n = 3.49), titanium oxide (n = 2.71), and silica (n = 1.50) materials. Both square lattice arrays and triangular lattice arrays have been studied. The two-dimensional photonic structures exhibited the Mach-Zehnder interferometer function that could be applied to optical switches or optical integrators. The beam splitter had the crossed linear defects shape, constructed by two orthogonal line defects. The ratio of defect radius to the lattice constant was 0.28, and the best moving distance has been 0.76 to achieve equal output energy.

show abstract

Section: Introduction *mentioning

confidence: 99%

Study of Two-Dimensional Photonic Crystal Arrays for Beam Splitters

Wu¹,

Ju²,

Chang³

et al. 2016

View full text Add to dashboard Cite

show abstract

“…[8][9][10] Meanwhile, LEE can be improved by patterning the substrate, 11,12 using epitaxial structure 13,14 or current spreading layers, 15,16 fabricating different LED configurations (conventional, flip-chip or vertical), or including photonic crystals. [17][18][19] Flip-chip LEDs (FCLEDs) possess a suitable configuration for high-power devices because of their effectiveness at increasing LEE and heat dissipation. 20 One of the major challenges to achieve high-performance FCLEDs is developing a high-quality metal stack with high reflectance and thermal conductivity that can serve as an efficient reflector with low forward voltage.…”

Section: Introductionmentioning

confidence: 99%

Improved performance of InGaN/GaN flip-chip light-emitting diodes through the use of robust Ni/Ag/TiW mirror contacts

Hasanov

Zhu

Sharma

et al. 2015

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

View full text Add to dashboard Cite

In this work, the authors report the incorporation of TiW alloy in InGaN/GaN-based flip-chip light-emitting diodes (LEDs). The advantages provided by the use of TiW are analyzed in detail. InGaN/GaN multiple quantum well LEDs with a Ni/Ag/TiW metal stack are found to tolerate high-temperature annealing better than those with a Ni/Ag metal stack. Highly improved current-voltage characteristics and enhanced optical output power are achieved for the devices with a TiW thin layer. These changes are ascribed to the higher reflectivity, smoother surface, and better ohmic properties of the device containing TiW after annealing. Better heat management of the device with TiW is demonstrated by comparing electroluminescence spectra of the two device structures. Overall, these factors resulted in devices with TiW exhibiting a higher external quantum efficiency than devices without TiW. Detailed x-ray photoelectron spectroscopy analyses of the reflector metal stacks reveal little intermixing of the layers after annealing in the devices with TiW. The results show that incorporation of TiW is a promising approach for the fabrication of high-performance InGaN/GaN flip-chip LEDs. V

show abstract

“…A more precise control of the surface nanopatterning could be developed by high energy focused gallium (Ga) ion beam technology. The technique provides one-step patterning and has been quite adaptive with complicated designs [9]. It saved time and processing steps in comparing dierent structures.…”

Section: Introductionmentioning

confidence: 99%

Ion Beam Surface Modification of GaN Films for High Efficient Light Emitting Diodes

Lin

2013

Acta Phys. Pol. A

Self Cite

View full text Add to dashboard Cite

Focused gallium (Ga) ion beam technology has been proposed to modify the surface of GaN thin lms. Due to the signicant advancement in nitride semiconductors, the solid-state light emitting diodes will gradually replace uorescent lamps in the next decade. However, further improvements in light extraction and power eciency are still highly desired. GaN is limited by its high refractive index, with low light escape cone angle at about 24.6• . The external quantum eciency is low due to the unwanted reection and absorption. As the patterning technology scales down to the nanometer level, photonic crystal lattice in the visible light wavelength range can be achieved. Therefore, we improved the external eciency by the new design of hexagonal photonic crystal lattice with air hole arrays in the diameter of 150 nm and the depth of 120 nm. The Ga beam was accelerated at 30 kV and the ion current was 100 pA. The plane wave expansion method along with the nite dierence time domain was useful to investigate the quantum connement. The nanopatterning by the focused ion beam could save time and processing step. In addition, we have successfully prepared blue InGaN/GaN samples with hexagonal period of 200 nm. The device micro-photoluminescence results have demonstrated that the peak illumination intensity was improved by 30%.

show abstract

Improved Light Extraction Efficiency by Photonic Crystal Arrays on Transparent Contact Layer Using Focused Ion Beams

Cited by 4 publications

References 9 publications

Study of Two-Dimensional Photonic Crystal Arrays for Beam Splitters

Study of Two-Dimensional Photonic Crystal Arrays for Beam Splitters

Improved performance of InGaN/GaN flip-chip light-emitting diodes through the use of robust Ni/Ag/TiW mirror contacts

Ion Beam Surface Modification of GaN Films for High Efficient Light Emitting Diodes

Contact Info

Product

Resources

About