This PDF file contains the front matter associated with SPIE Proceedings Volume 9768, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

The controlled growth of highly n-doped GaN micro rods is one of the major challenges in the fabrication of recently developed three-dimensional (3D) core-shell light emitting diodes (LEDs). In such structures with a large active area, higher electrical conductivity is needed to achieve higher current density. In this contribution, we introduce high quality heavily-doped GaN:Si micro-rods which are key elements of the newly developed 3D core-shell LEDs. These structures were grown by metal-organic vapor phase epitaxy (MOVPE) using selective area growth (SAG). We employed spatially resolved micro-Raman and micro-photoluminescence (PL) in order to directly determine a free-carrier concentration profile in individual GaN micro-rods. By Raman spectroscopy, we analyze the low-frequency branch of the longitudinal optical (LO)-phonon-plasmon coupled modes and estimate free carrier concentrations from ≈ 2.4 × 10¹⁹ cm−3 up to ≈ 1.5 × 10²⁰ cm^-3. Furthermore, free carrier concentrations are determined by estimating Fermi energy level from the near band edge emission measured by low-temperature PL. The results from both methods reveal a good consistency.

White light-emitting diodes (wLEDs) are the new environmental friendly sources for general lighting purposes. For applications requiring a high-brightness, current wLEDs present overheating problems, which drastically decrease their emission efficiency, color quality and lifetime. This work gives an overview of the recent investigations on single-crystal phosphors (SCPs), which are proposed as novel alternative to conventional ceramic powder phosphors (CPPs). This totally new approach takes advantage of the superior properties of single-crystals in comparison with ceramic materials. SCPs exhibit an outstanding conversion efficiency and thermal stability up to 300°C. Furthermore, compared with encapsulated CPPs, SCPs possess a superior thermal conductivity, so that generated heat can be released efficiently. The conjunction of all these characteristics results in a low temperature rise of SCPs even under high blue irradiances, where conventional CPPs are overheated or even burned. Therefore, SCPs represent the ideal, long-demanded all-inorganic phosphors for high-brightness white light sources, especially those involving the use of high-density laser-diode beams.

Ultraviolet light-emitting diode (UV LED) adoption is accelerating; they are being used in new applications such as UV curing, germicidal irradiation, nondestructive testing, and forensic analysis. In many of these applications, it is critically important to produce a uniform light distribution and consistent surface irradiance. Flat panes of fused quartz, silica, or glass are commonly used to cover and protect multi-UV LED arrays. However, they don’t offer the advantages of an optical lens design. An investigation was conducted to determine the effect of a secondary glass optic on the uniformity of the light distribution and irradiance. Glass optics capable of transmitting UV-A, UV-B, and UV-C wavelengths can improve light distribution and intensity. In this study, a UV transmitting glass formulation and secondary linear optic were designed and manufactured to demonstrate their effects on achievable irradiance intensity and uniformity. Prismatic patterning on the light source surface of the lens was used to minimize reflection losses on the incident surface of the glass. Fresnel optics were molded into the opposite side of the UV transmitting glass to control the refraction of the light and to gain the desired light intensity distribution from two multi-UV LED arrays. A 20% increase in relative irradiance was observed while maintaining the same coverage area. This work discusses the optical design and the resulting benefits of controlled light output on UV LED systems, which include reduced driving current, decreased thermal deterioration, improved energy efficiency, and longer LED lifetime.

State-of-the art light-emitting diodes (LEDs) for solid-state lighting (SSL) are reviewed with the focus on their efficiency and ways for its improvement. Mechanisms of the LED efficiency losses are considered on the heterostructure, chip, and device levels, including high-current efficiency droop, recombination losses, “green gap”, current crowding, Stokes losses, etc. Materials factors capable of lowering the LED efficiency, like composition fluctuations in InGaN alloys and plastic stress relaxation in device heterostructures, are also considered. Possible room for the efficiency improvement is discussed along with advanced schemes of color mixing and LED parameters optimal for generation of high-quality white light.

The thermal droop (reduction of the optical power when the temperature is increased) is a phenomenon that strongly limits the efficiency of InGaN-based light-emitting diodes. In this paper we analyze the role of Shockley-Read-Hall (SRH) recombination and of the electron blocking layer (EBL) in the process by using numerical simulations and literature data. The benefic impact of EBL suggests that carrier escape from the quantum wells gives a significant contribution to the thermal droop, therefore we review some of the mechanisms described in the literature (thermionic emission, phonon-assisted tunneling, thermionic trap-assisted tunneling). Since no formulation is able to fit the behavior of the measured SQW devices, we develop a new model based on two phonon-assisted tunneling steps through a defective state, extended in order to take into account zero-field emission. By using experimental data, material constants from the literature and only two fitting parameters the model is able to reproduce the experimental behavior.

The emission profiles of light-emitting diodes have typically be measured by goniophotometry. However this technique suffers from several drawbacks, including the inability to generate three-dimensional intensity profiles as well as poor spatial resolution. These limitations are particularly pronounced when the technique is used to compared devices whose emission patterns have been modified through surface texturing at the micrometer and nanometer scales,. In view of such limitations, confocal microscopy has been adopted for the study of emission characteristics of LEDs. This enables three-dimensional emission maps to be collected, from which two-dimensional cross-sectional emission profiles can be generated. Of course, there are limitations associated with confocal microscopy, including the range of emission angles that can be measured due to the limited acceptance angle of the objective. As an illustration, the technique has been adopted to compare the emission profiles of LEDs with different divergence angles using an objective with a numerical aperture of 0.8. It is found that the results are consistent with those obtained by goniophotometry when the divergence angle is less that the acceptance angle of the objective.

Two blue (450 nm) light–emitting diodes (LED), which only differ in top p-GaN layer growth conditions, were comparatively investigated. I-V, C-V, TLM, Electroluminescence (EL) and Photoluminescence (PL) techniques were applied to clarify a correlation between MOCVD carrier gas and internal properties. The A-structure grown in the pure N₂ environment demonstrated better parameters than the B-structure grown in the N₂/H₂ (1:1) gas mixture. The mixed growth atmosphere leaded to an increase of sheet resistances of p-GaN layer. EL and PL measurements confirmed the advantage of the pure N₂ utilization, and C(V_R) measurement pointed the increase of static charge concentration near the p-GaN interface in the B structure.

GaN-based resonant-cavity light-emitting diode (RCLED) has a circular output beam with superior directionality than conventional LED and has power scalability by using two-dimensional-array layout. In this work, blue RCLEDs with a top reflector of approximately 50% reflectance were fabricated and characterized. An output power of more than 0.5 mW per diode was achieved before packaging under room-temperature continuous-wave (CW) operation. The full width at half maximum (FWHM) of the emission spectrum was approximately 3.5 and 4.5 nm for 10- and 20-μm-diameter devices, respectively. And the peak wavelength as well as the FWHM remained stable at various currents and temperatures.

Single-mode superluminescent diodes operating at 2 μm wavelength are reported. The structures are based on GaSb material systems and were fabricated by molecular beam epitaxy. Several waveguide designs have been implemented. A continuous-wave output power higher than 35 mW is demonstrated for a spectrum centered at around 1.92 μm. We show that the maximum output power of the devices is strongly linked to spectrum width. Device having low output power exhibit a wide spectrum with a full-width half-maximum (FWHM) as large as 209 nm, while devices with highest output power exhibit a narrower spectrum with about 61 nm FWHM.

Today’s InGaN-based white LEDs still suffer from a significant efficiency reduction at elevated current densities, the so-called “Droop”. Core-shell microrods, with quantum wells (QWs) covering their entire surface, enable a tremendous increase in active area scaling with the rod’s aspect ratio. Enlarging the active area on a given footprint area is a viable and cost effective route to mitigate the droop by effectively reducing the local current density. Microrods were grown in a large volume metal-organic vapor phase epitaxy (MOVPE) reactor on GaN-on-sapphire substrates with a thin, patterned SiO2 mask for position control. Out of the mask openings, pencil-shaped n-doped GaN microrod cores were grown under conditions favoring 3D growth. In a second growth step, these cores are covered with a shell containing a quantum well and a p-n junction to form LED structures. The emission from the QWs on the different facets was studied using resonant temperature-dependent photoluminescence (PL) and cathodoluminescence (CL) measurements. The crystal quality of the structures was investigated by transmission electron microscopy (TEM) showing the absence of extended defects like threading dislocations in the 3D core. In order to fabricate LED chips, dedicated processes were developed to accommodate for the special requirements of the 3D geometry. The electrical and optical properties of ensembles of tens of thousands microrods connected in parallel are discussed.

Silicon substrates offer a variety of advantages over conventional LED substrates, including both their low cost and their compatibility with the existing semiconductor manufacturing infrastructure. Researchers have sought to avail themselves of these benefits by developing GaN LEDs on silicon substrates. Integration of the two materials, however, presents several technical challenges that have proven difficult to address. The main challenges are the large lattice mismatch between GaN and silicon and the large difference in thermal expansion coefficients. Solutions have begun to emerge in recent years, with Toshiba being the first to commercialize GaN-on-Si technology on 200mm substrates in 2013, and several companies now shipping GaN-on-Si LEDs. Toshiba has developed a novel buffer layer structure and MOCVD growth technology that controls strain, wafer bow, and cracking while also suppressing formation of dislocations. This technology allows for the growth of GaN epitaxial layers with minimal cracking and dislocation densities in the low 10⁸ cm^-2. Control of strain and wafer bow is critical for the epitaxial process, and this requires very fine control over both absolute wafer temperature and temperature uniformity. Toshiba’s technology controls temperature uniformity very well, and Toshiba has demonstrated wavelength uniformity with σ=2nm across a 200mm wafer. Thin film LEDs fabricated from these materials have efficiencies on par with the best efficiencies of LEDs grown on conventional substrates. Blue LED wall-plug efficiencies of ~83% are demonstrated.

LED have become the main light sources of the future as they open the path for intelligent use of light in time, intensity and color. In many usages, strong energy economy is done by adjusting these properties. The smart lighting has three dimensions, energy efficiency brought by GaN blue emitting LEDs, integration of electronics, sensors, microprocessors in the lighting system and development of new functionalities and services provided by the light. Monolithic LED arrays allow two major innovations, the spatial control of light emission and the adjustment of the electrical properties of the source.

microLED arrays are a route to providing emissive displays with high brightness and low power consumption performance. In this talk we will discuss results pertaining to sub 10 μm LED pixels, the challenges posed and performance achieved in forming microLED arrays. In particular, pixel pitch, backplane capabilities and colourisation. The applications which can benefit from this approach will also be discussed.

Although LEDs have been introduced successfully in many general lighting applications during the past decade, high brightness light source applications are still suffering from the limited luminance of LEDs. High power LEDs are generally limited in luminance to ca 100 Mnit (10⁸ lm/m²sr) or less, while dedicated devices for projection may achieve luminance values up to ca 300 Mnit with phosphor converted green. In particular for high luminous flux applications with limited étendue, like in front projection systems, only very modest luminous flux values in the beam can be achieved with LEDs compared to systems based on discharge lamps. In this paper we introduce a light engine concept based on a light converter rod pumped with blue LEDs that breaks through the étendue and brightness limits of LEDs, enabling LED light source luminance values that are more than 4 times higher than what can be achieved with LEDs so far. In LED front projection systems, green LEDs are the main limiting factor. With our green light emitting modules, peak luminance values well above 1.2 Gnit have been achieved, enabling doubling of the screen brightness of LED based DLP projection systems, and even more when this technology is applied to other colors as well. This light source concept, introduced as the ColorSpark High Lumen Density (HLD) LED technology, enables a breakthrough in the performance of LED-based light engines not only for projection, where >2700 ANSI lm was demonstrated, but for a wide variety of high brightness applications.

High power LEDs were introduced in automotive headlights in 2006-2007, for example as full LED headlights in the Audi R8 or low beam in Lexus. Since then, LED headlighting has become established in premium and volume automotive segments and beginning to enable new compact form factors such as distributed low beam and new functions such as adaptive driving beam. New generations of highly versatile high power LEDs are emerging to meet these application needs. In this paper, we will detail ongoing advances in LED technology that enable revolutionary styling, performance and adaptive control in automotive headlights. As the standards which govern the necessary lumens on the road are well established, increasing luminance enables not only more design freedom but also headlight cost reduction with space and weight saving through more compact optics. Adaptive headlighting is based on LED pixelation and requires high contrast, high luminance, smaller LEDs with high-packing density for pixelated Matrix Lighting sources. Matrix applications require an extremely tight tolerance on not only the X, Y placement accuracy, but also on the Z height of the LEDs given the precision optics used to image the LEDs onto the road. A new generation of chip scale packaged (CSP) LEDs based on Wafer Level Packaging (WLP) have been developed to meet these needs, offering a form factor less than 20% increase over the LED emitter surface footprint. These miniature LEDs are surface mount devices compatible with automated tools for L2 board direct attach (without the need for an interposer or L1 substrate), meeting the high position accuracy as well as the optical and thermal performance. To illustrate the versatility of the CSP LEDs, we will show the results of, firstly, a reflector-based distributed low beam using multiple individual cavities each with only 20mm height and secondly 3x4 to 3x28 Matrix arrays for adaptive full beam. Also a few key trends in rear lighting and impact on LED light source technology are discussed.

The key issue for light emission strength of GaN-based LEDs is the high defect density and strain in MQWs causing the electric polarization fields. In this work, we construct 3D confocal microspectroscopy to clarify strain distribution and the relationship between photoluminescence (PL) intensity and pattern sapphire substrate (PSS). From 3D construction of E₂^high Raman and PL mapping, the dislocation in MQW can be traced to the cone tip of PSS and the difference in E₂^high Raman mapping between substrate and surface is also measured. The ability to measure strain change in 3D structure nondestructively can be applied to explore many structural problems of GaN-based optoelectronic devices.

With the introduction of solid state light sources, the variety in emission spectra is almost unlimited. However, the set of standardized parameters to characterize a white LED light source, such as correlated color temperature (CCT) and CIE general color rendering index (R_a), is known to be limited and insufficient for describing perceived differences between light sources. Several characterization methods have been proposed over the past decades, but their contribution to perceived color quality has not always been validated. To gain more insight in the relevant characteristics of the emission spectra for specific applications, we have conducted a perception experiment to rate the attractiveness of three sets of objects, including fresh food, packaging materials and skin tones. The objects were illuminated with seven different combinations of Red, Green, Blue, Amber and White LEDs, all with the same CCT and illumination level, but with differences in Ra and color saturation. The results show that, in general, object attractiveness does not correlate well with R_a, but shows a positive correlation with saturation increase for two out of three applications. There is no clear relation between saturation and skin tone attractiveness, partly due to differences in preference between males and females. A relative gamut area index (G_a) represents the average change in saturation and a complementary color vector graphic shows the direction and magnitude of chromatic differences for the eight CIE-1974 test-color samples. Together with the CIE general color rendering index (R_a) they provide useful information for designing and optimizing application specific emission spectra.

With this work we report on the design of an LED based star simulator. The simulator is the result of a cooperation between the Italian National Astrophysics Institute and LightCube SRL, a University of Padova (Italy) R&D spin-off. The simulator is designed to achieve a luminous output customizable both in spectrum and in intensity. The core of the system is a 25 channels independent LED illuminator specifically designed to replicate the spectral emission of the desired star. The simulated star light intensity can also be carefully tuned to achieve the correct illuminance at a specific distance from the star.

Development and manufacturing of LED structures is still driven by production cost reduction and performance improvements. Therefore, in-situ monitoring during the epitaxial process plays a key role in view of further yield improvement and process optimization. With the continuing trend towards larger wafers, stronger bow and increased aspherical curvature are additional challenges the growers have to face, leading to non-uniform LED-emission. Compared to traditional in-situ metrology like curvature measurement and near UV pyrometry, in-situ photoluminescence measurements can provide a more direct access to the quantum well emission already during growth. In this paper we show how in-situ photoluminescence measurements can be used in a production type multi-wafer MOCVD system to characterize the quantum well emission already during growth. We also demonstrate how deviations from the desired wavelength can be detected and corrected in the same growth run. Since the method is providing spatially resolved line-scans across the wafer, also the uniformity of the emission wavelength can be characterized already during growth. Comparison of in-situ and ex-situ photoluminescence data show excellent agreement with respect to wavelength uniformity on 4 inch wafers.

Ex-situ sputtered AlN nucleation layer has been demonstrated effective to significantly improve crystal quality and electrical properties of GaN epitaxy layers for GaN based Light-emitting diodes (LEDs). In this report, we have successfully reduced X-ray (102) FWHM from 240 to 110 arcsec, and (002) FWHM from 230 to 101 arcsec. In addition, reverse-bias voltage (Vr) increased around 20% with the sputtered AlN nucleation layer. Furthermore, output power of LEDs grown on sputtered AlN nucleation layer can be improved around 4.0% compared with LEDs which is with conventional GaN nucleation layer on pattern sapphire substrate (PSS).

This paper critically reviews the most relevant failure modes and mechanisms of InGaN LEDs for lighting application. At chip level, both the epitaxial heterostructure and the ohmic contacts may be affected. This may result in: (i) the formation of defects within the active region, resulting in the increase of non-radiative recombination and leakage current, (ii) the reduction of the injection efficiency consequent to increased trap-assisted tunneling, (iii) the degradation of contact resistance with increase of forward voltage. Package-related failures – not described in this paper - include (iv) thermally-activated degradation processes, affecting the yellow phosphors, the plastic package or the encapsulating materials and (v) darkening of the Ag package reflective coating, the latter due to chemical reaction with contaminants as Cl or S. In order to enucleate and study the different physical failure mechanisms governing device degradation, single quantum well (SQW) blue LEDs, InGaN laser structures and commercially-available white LEDs to high temperature and/or high current density have been submitted to accelerated testing at high temperature and high current density.

We report on blue and green light-emitting-diodes (LEDs) grown on (11-22)-GaN templates. The templates were created by overgrowth on structured r-plane sapphire substrates. Low defect density, 100 mm diameter GaN templates were obtained by metal organic vapour phase epitaxy (VPE) and hydride VPE techniques. Chemical-mechanical polishing was used to obtain smooth surfaces for the subsequent growth of LED structures. Ohmic contacts to the p-type GaN were obtained despite the lower activated acceptor levels. The LEDs show excellent output power and fast carrier dynamics. Freestanding LEDs have been obtained by use of laser-lift-off. The work is the result of collaboration under the European Union funded ALIGHT project.

We present the growth, fabrication, and characterization of light-emitting diodes based on (Al,Ga)As quantum wells and dots embedded in a p-n GaP structure. Samples were grown on Sulphur-doped GaP (001) substrate using gas-source molecular beam epitaxy. The structures include either GaAs quantum structures with nominal coverage between 1.2 and 3.6 monolayers or Al_0.3Ga_0.7As quantum wells. For structures with GaAs layer thicker than 1.5 monolayers the 3.6% lattice mismatch in the materials system results in formation of quantum dots via Stranski-Krastanow growth mode with areal density of about 8×10¹⁰ cm^-2. The atomic-force and transmission-electron microscopy show that with increasing coverage of GaAs from 1.8 to 3.6 monolayers the average lateral size and height of dots change in the range of 17-34 nm and 0.9–2 nm, respectively. The diode structures emit light from the red to the green spectral range up to room temperature. The GaAs/GaP QDs show electroluminescence between 1.8 eV and 2 eV, whereas the Al_0.3Ga_0.7As quantum wells emit light between 2 eV and 2.2 eV.

The integration of light emitting devices on silicon substrates has attracted intensive research for many years. In contrast to the InGaN light emitting diodes (LEDs) whose epitaxy technology on Si substrates is robust and mature, the epitaxy of other compound semiconductor light emitting materials covering the visible wavelength range on Si is still challenging. We have studied epitaxial growth of red InGaP light emitting materials on engineered Ge-on-Si substrates. Ge-on-Si was grown on 8’’ Si substrates in a metal organic chemical vapour deposition (MOCVD) reactor using two- step growth and cycling annealing. Threading dislocation densities (TDDs) were controlled to as low as 10⁶/cm² by using As-doped Ge initiation. A GaAs buffer layer and lattice-matched InGaP LEDs were grown on the Ge-on-Si sequentially in the same MOCVD process and red LEDs are demonstrated. InGaP multiple-quantum-well LED structures were grown on full 8’’ Ge-on-Si substrates and characterized.

Efficiency of commercial 620 nm AlGaInP Golden Dragon-cased high-power LEDs has been studied under extremely high pump current density up to 4.5 kA/cm² and pulse duration from microsecond down to sub-nanosecond range. To understand the nature of LED efficiency decrease with current, pulse width variation is used. Analysis of the pulse-duration dependence of the LED efficiency and emission spectrum suggests the active region overheating to be the major factor controlling the LED efficiency reduction at CW and sub-microsecond pumping. The overheating can be effectively avoided by the use of sub-nanosecond current pulses. A direct correlation between the onset of the efficiency decrease and LED overheating is demonstrated.

Laser jamming has two forms: passive and active jamming. In this paper we compare between the passive, active and passive-active deception techniques from the functional point of view. Passive jamming techniques are used with highly absorptive or diffusive materials on the body of the equipment. These passive techniques decrease the intensity of the reflected laser pulses and hence decrease SNR. Active jamming techniques are used to deceive and puzzle laser receivers. A high energy pulse with delay time is transmitted with each reflected pulse then the receiver will confuse between the two pulses. Active jammers need higher energy pulses to provide high jammer to signal ratio. In this paper we will compare received pulses using passive technique only, active technique only and passive-active technique. We use Q-switched Nd:YAG Laser source with wavelength of 1064 nm, energy of 80 mJ, pulse width of 200 μs and repetition rate 10-20 Hz. The intensity of the incident laser pulse is reduced by a factor of 80 % using an absorptive material, at the same time an electronic circuit receives the laser pulses and use it to trigger high-power LEDs with the same laser wavelength that make phase shift and signal distortion to the received pulses. The results show that the passive-active technique is the optimum one and solve the two disadvantages of each passive and active technique as individual. It decreases the reflected signal amplitude and hence the jammer to signal ratio can be obtained with lower power sources and increases the complexity for the DSP-based systems.

Although performance of LEDs has been raised dramatically, wall-plug efficiency (WPE) of commercial high-power large-area (I ≥ 1 A) devices remains low given that the LEDs performance is close to that of the other optoelectronic devices. Instead of numerous studies aimed to increase optical efficiency that tends to saturate, we are concerned about electrical efficiency (epsilon_el). In this paper, we consider inevitable electrical losses paid for carrying electrons into the active region before they recombine. More specifically, we are interested in the inherent limitations imposed on the WPE and epsilon_el by the series resistance, current crowding effect, dimensions of chips, and ideality factor (β). The study was performed on commercial vertical InGaN-on-SiC multiple-quantum well LEDs with rated currents (I_r) of about 1A. All parameters are obtained exclusively from I-V characteristics. We show that a) epsilon_el losses remarkably affect WPE even at I << I_r, b) the I_r values fall into high-current domain, c) 2D current distribution suffers of severe crowding, d) voltage drop on series resistance cannot be neglected, e) the dominant mechanism of carrier transport across the junction is carrier recombination inside the depletion region (β ≈ 2). We discuss advantages and disadvantages of industrial GaInN/SiC technology from the point of view of electrical efficiency and consider an alternative approach to make high-power LEDs more efficient.

Luminescent epitaxial β-FeSi₂ grains were grown on the Si (111) substrates precoated with Au-layer. These epitaxial β- FeSi₂ grains had (101)/(110)-preferred orientation and were constructed with two kinds of triple-domain structure. The Au-Si liquid phase obtained by the Au-Si eutectic reaction contributed to the formation of such β-FeSi₂ grains on the Si (111) surface. Clear photoluminescence (PL) spectrum of β-FeSi₂ were observed up to 240 K that indicated the formation of high-quality crystals with the low density of the non-radiative recombination center in the grains.

The Solid-State Lighting (SSL) industry utilizes semiconductor based light-emitting diodes (LEDs) as core elements of light sources. LED lighting has several advantages over conventional incandescent bulbs; however, device-level issues such as material quality, low quantum efficiencies, and low light extraction efficiencies still exist. Many techniques have been explored to provide improvement in the area of LED light extraction. Improvement in light extraction efficiency, through the use of integrated optical components such as photonic crystals, is critical for the improvement in the overall efficiency of the device. Fabrication and integration of PhCs into LEDs with little or no degradation in device’s electrical characteristics is an important accomplishment to be considered. Use of electron beam lithography and novel electron beam resists like hydrogen silsesquioxane will allow advancements toward achieving this goal. The unique chemical properties of HSQ allows transformation of the patterned resist into silicon dioxide. This leads to hybrid PhC structures that contain the cured form of HSQ and other materials of interest in an LED. In this work, novel hybrid PhC structures in square and triangular lattice configurations will be modeled to improve light extraction in blue InGaN/GaN based LEDs (λ=465 nm) and attain an optimal structure. Feature sizes from 100 nm to 465 nm will be modeled and the effect of the patterned structure (band gap and/or diffraction) on the light extraction will be studied and analyzed. Simulation data from frequency domain and time domain engines in MPB and OptiFDTD respectively will be analyzed and presented.