This PDF file contains the front matter associated with SPIE Proceedings Volume 6797, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

Marketing studies by EPIC show significant revenue opportunities by 2012 for UHB-LEDs in the automotive, LCD backlighting, and architectural lighting sectors. The goal of this workshop on manufacturing issues is to consider five key issues for UHB-LED manufacturing and to propose solutions that will pave the way to full exploitation of the opportunities.

With an annual volume of more than 5 million units of 2" equivalent substrates, GaN-based LED is the main eater of nitride materials targeting a $3.5B market at devices level. The next big challenge for LED business is to take market shares over the general lighting industry and dollar per lumen ($/lm) ratio is the key parameter. Numerous technological improvements are under investigation: - At die level, photonic crystals and surface texturing technologies are jointly developed to increase the light extraction. External Quantum Efficiency EQE has now reached > 75% at R&D level. - At material level, there is a rapid emergence of new substrates for GaN epitaxy and composite substrates in 6" diameter. That is opening new doors to higher LED luminous efficiency and cost reduction toward the gigantic SSL general illumination business.

The development of brand specific front and tail lights in cooperation with the stylists is the assignment of automobile lighting. Highest car safety, attractive styling, differentiation in the traffic situation and environment friendliness are the project limits. LED technology has the potential to extend these limits. The LED technology will have to improve, but it is also enhanced by new sensor technologies that introduce new functionalities. The implementation of a possible roadmap depends on right technologies at the right time. For new styling ideas and functional innovations further steps in lighting technology are necessary. The document will show a car makers view on possible innovation ideas.

In this paper we give a summary of technologies that are essential for phosphor developing: Characterization of the pure phosphor powders with methods like powder X-ray diffraction (XRD), optical spectroscopy, scanning electron microscopy (SEM), etc. give strong hints for and how to improve the phosphor's performance. The final proof of the phosphor's quality is obtained by application testing in the LED. Latter is a very useful tool for materials researchers and developers to adopt the phosphor to the LED device. Last but not least we demonstrate advantages of a phosphor fabrication process by using wet chemical routes in comparison to the traditional and widely applied solid state diffusion methods ("mix & fire").

Light emitting diodes have been an option in automotive lighting for more than 15 years now. The capacities and colours of LEDs available in the recent past were sufficient to realize interior lighting and rear signalling functions. In the meantime, series applications, such as position or daytime running lights, using white LEDs for signal functions in headlamps, are no longer a rarity. The next step - realizing main lighting functions for series applications - is imminent. LED will offer a multitude of styling options in rear and front lighting, as well as a light colour which differs considerably from that of the previous halogen and xenon headlamp systems. The further advantages of the LED compared with conventional light sources with regard to service life, power efficiency and package space requirements can thus only be sensibly exploited by means of suitable structural and connection techniques. Increasing complexity and installation conditions in an often rough environment are demanding challenge to realize the hardware of LED lamps. In this paper at first the requirements on LEDs and LED modules in automotive exterior lighting will be discussed. Furthermore the status of industrialization and modular concepts for signal lamps and full LED headlamps will be presented. The paper will finish with a discussion of new headlamp active lighting functions like maker light or glare free high beam, implemented in hybrid or with pure LED technology. In the subsequent headlamp integration, from about 2012, freely-addressable LED-Arrays will possibly enable these new types of lighting functions.

With the new Generation of InGaN-based thinfilm Chips efficacies of 110/lm/W and output power of 32 mW at 20 mA (5 mm Radial lamp, 438nm, chip-size 255&mgr;m x 460&mgr;m) are reached. Due to the scalability of the ThinGaN concept chip brightness and efficiency are scalable to larger chip sizes: the brightness achieved for a 1 mm2 ThinGaN Power chip at 350 mA were 495mW (445nm) and 202mW or 100 lm (527nm). White LEDs with phosphorus achieved 102 lm at 350mA, mounted in an OSTAR module with six LED chips 1200 lm were demonstrated at 1000 mA driving current. White emitting automotive headlamp modules with 620lm (5x 1mm2 chip at 700mA) and 41 MCd/m2 as well as green emitting projection modules with 57 MCd/m2 at 2A/mm2 drive current and 12mm2 chip area are realized. These technological improvements demonstrate the straight way of GaInN-LEDs for Solid State lighting.

In this paper we present HyLED, a silicon wafer packaging solution for high-brightness LEDs. The associated technology is batch micro-machining/metallisation processing of silicon wafers allowing significant reduction of the final device size. The presented package is multi-functional where the micro-machined cavity acts as reflector, thermal conductor and reservoir for the silicone/colour conversion substance. The base material, silicon, has excellent mechanical and thermal properties and enables direct integration of intelligence. We present customer specific solutions, open tool samples and performance data for optical and thermal parameters and reliability testing. Thermal resistance values of R<5 K/W, junction-to-board are demonstrated.

Phosphor converted Light Emitting Diodes (pcLED) have undergone many changes of design over the last 11 years. For advanced applications, however, besides other binning criteria a closely binned color point appears to be a major issue. Manufacturing yield is closely related to this point. Philips Lumileds Lighting (PLL) introduced very recently a new compact solid state color converter - Lumiramic - which allows much closer color control by selecting perfect matches between blue pump LEDs and previously characterized converter tiles in a pick-and-place process. Lumiramic phosphor technology utilizes a ceramic phosphor plate and PLL's new Thin Film Flip Chip (TFFC) technology. A first application in Automotive Forward Lighting and some of the design considerations are outlined in the paper

In this paper different technologies for LED packaging are compared, focusing on Chip on Board (COB) and SMD technology. The package technology which is used depends on the LED application. A critical fact in LED technology is the thermal management, especially for high brightness LED applications because the thermal management is important for reliability, lifetime and electrooptical performance of the LED module. To design certain and long life LED applications knowledge of the heat flow from LEDs to the complete application is required. High sophisticated FEM simulations are indispensable for modern development of high power LED applications. We compare simulations of various substrate materials and packaging technologies simulated using FLOTHERM software. Thereby different substrates such as standard FR4, ceramic and metal core printed circuit boards are considered. For the verification of the simulated results and the testing of manufactured modules, advanced measurement tools are required. We show different ways to experimentally characterize the thermal behavior of LED modules. The thermal path is determined by the transient thermal analysis using the MicReD T3Ster analyzer. Afterwards it will be compared to the conventional method using thermocouples. The heat distribution over the module is investigated by an IR-Camera. We demonstrate and compare simulation and measurement results of Chip-on-Board (COB) and Sub-Mounted Devices (SMD) technology. The results reveal that for different applications certain packages are ideal.

Initial results are presented on the electroless deposition of metal contacts to p-type gallium nitride (GaN). Deposition procedures were developed for the deposition of both nickel and tungsten-cobalt (W-Co) contacts onto p-type GaN. Attempts to deposit platinum on p-type GaN failed, despite the fact that electroless platinum deposition was successfully achieved on other substrate types. Nickel contacts were overlaid with gold and annealed in oxygen ambient to form ohmic contacts with specific contact resistivity values down to 2x10-2 &OHgr;cm2. Measurements at elevated temperatures up to 140 degrees C showed that the specific contact resistivity was almost independent of temperature. The tungsten-cobalt contacts showed rectifying behaviour even after annealing at 650 degrees C. This makes this contact type a possible candidate for Schottky contacts in high temperature applications.

An important issue for white ultra high power LEDs is the generation of a homogeneous light with high efficiency and a good color rendering index. Different from hot light sources LEDs do not emit the whole range of visible wavelengths. Only a certain wavelength with a limited full width at half maximum is emitted. Therefore a combination of wavelengths must be used to satisfy the human eye for white light. The CIE chromaticity diagram (Fig. 1) shows, that several combinations of wavelengths let the brain realize white light. Already the combination of two wavelengths (e.g. cyan and red or blue and yellow) let us think, that the source is white, if this wavelengths hit our receptors. This is completely different, if the light is illuminating an object. The reflection spectra of this object, which is crucial for our color feeling about this object, can not be stimulated in the whole range. For example a red stop sign, which is absorbing all wavelength excepting red, will absorb the blue and yellow light from our "white" light source and due to the missing red, the sign seems to be dark grey or black.

As LEDs became the preferred light source for coloured light, the focus is now on improving the performance of white LEDs, to achieve the required levels for applications such as general lighting. One especially interesting automotive application of white LEDs are daytime running lights, which may become mandatory in the near future in Europe. In this application the specific advantages of LEDs like long lifetime, high efficiency, robustness and freedom for the designers can be fully employed. The most common way to realize a white LED is the approach of a luminescence conversion LED, where blue light of a GaN Chip is partly transformed into yellow light by a phosphor. The combination of the not converted blue and the yellow light results in white light. A strong increase of the luminous flux becomes possible by the use of High Power LED Chips, high efficient yellow phosphors and a packaging that offers an excellent thermal management. First of all, the application of a High Power LED Chip allows an increase of the electrical current up to 1 Ampere. While this increases the light output significantly, the thermal management of the LED package has to be improved in order to remove the heat created by the LED chip. Apart from chip efficiency and driving current the brightness of a white LED also strongly depends on the efficiency of the used phosphor. Today's typically used phosphors are for example YAG:CE, or with Europium 2+ doped compounds. The required quantum efficiency should be higher than 90% for good results in the luminous efficiency. Furthermore, for certain applications such as automotive front lighting the converter even has to be stable under temperature conditions up to 120°C, be resistant to humidity and guarantee a long lifetime. In this contribution we will present a comparison of several different types of phosphors with emphasis on their temperature dependent behaviour.

The performance of a series of near-UV (~385 nm) emitting LEDs, consisting of high efficiency InGaN/AlInGaN QWs in the active region, was investigated. Significantly reduced roll-over of efficiency at high current density was found compared to InGaN/GaN LEDs emitting at a similar wavelength. The importance of optical cavity effects in flip-chip geometry devices has also been investigated. The light output was enhanced by more than a factor of 2 when the light-emitting region was located at an anti-node position with respect to a high reflectivity current injection mirror. A power of 0.49 mW into a numerical aperture of 0.5 was obtained for a junction area of 50 micrometers in diameter and a current of 30 mA, corresponding to a radiance of 30 W/cm2/str.

LEDs based on semiconductor nanowires are a promising alternative to the standard planar devices to achieve low cost high yield manufacturing for the general lighting applications. The expected advantages of such structures are a high crystalline quality of the heterostructures, compliance with a large range of substrates and light extraction enhancement. We report here on the present status of our research work concerning the electromagnetic simulation of nanowire emission, the epitaxy of near-UV semiconductor vertically aligned nanowires, the collective integration technology of these nanowires and their characterizations.

Thermal analysis of wafer-level packaged LEDs with red, green and blue multi-chips are investigated. With Si-MEMS technology, wafer-level packaged LEDs are useful for the high power applications such as back light unit (BLU) and general solid state lighting due to the compactness and integrated fabrication process. In this paper, thermal characteristics of wafer-level packaged white LEDs with multi-chips are investigated using both serial and matrix measurement methods.

Optical and structural properties of InGaN/GaN multi-quantum well (MQW) structures with different well width, influenced by the nano-structural features in the MQWs, were investigated by optical measurements of photoluminescence (PL), photoluminescence excitation (PLE) and time-resolved photoluminescence (TRPL), as well as structural analysis methods, such as high-resolution X-ray diffraction (HRXRD) and high-resolution transmission electron microscopy (HRTEM) measurements. Due to the quantum confined Stark effect (QCSE), larger Stokes shift is induced with larger well width. Thermally activated carrier screening model is established to well describe the so-called S-shaped spectral shift with temperature. Inhomogeneous line-width broadening induced by piezoelectric field is found to be dominant at low temperature, while homogeneous line-width broadening due to phonon scattering takes over at higher temperature. Additionally, two activation energies are extracted from the Arrhenius plot of PL intensity. One is assigned to be the exciton binding energy and the other one the confinement energy of electrons in the quantum well. TRPL study further indicated that the radiative lifetime was decreased with the decreased well width. All these are associated with the In-composition fluctuation and nano-structures in the MQWs.

MOVPE grown InGaN multiple-quantum-well (MQW) light emitting diodes (LEDs) on c-plane (0001) sapphire emitting at 375 nm with GaN, Al0.16Ga0.84N and InxAl0.16GaN-barrier layers were investigated in order to study the influence of the barrier composition on the light output characteristics of near UV devices. By substituting the GaN barrier layers with Al0.16Ga0.84N the output power increased 30-fold due to the increased band-offset between the In0.03Ga0.97N QWs and the barriers. The addition of 3.3% indium to the AlGaN barriers resulted in a reduction of the FWHM, and a 50-fold increase in light output power compared to LEDs with GaN barriers. Even though the band-offset and hence the carrier confinement for the InAlGaN barriers is smaller than in the case of AlGaN barriers, strain compensated In0.03Al0.16Ga0.79N barrier layers seem to be greatly beneficial for the external quantum efficiency of the near UV LEDs. The effect of an n-type Al0.23Ga0.77N hole-blocking-layer, which was inserted below the MQW stack to prevent hole carrier leakage from UV LED active region, on the light output was also investigated. By incorporating strain compensated In0.03Al0.16Ga0.79N barriers and an Al0.23Ga0.77N hole blocking layer we were able to realize 375 nm LEDs with an output of 1 mW (measured on-wafer) at 100 mA. Finally, the wavelength dependence of the light output from UV LEDs with InGaN MQWs emitting between 375 nm and 381 nm with peak output power of 4 mW at 200 mA for the longer wavelength devices is shown.

As a light source the LED has some advantage over the traditionally used fluorescence tube such as longer life or lower space consumption. Consequently customers are asking for the LED lighting design in their products. We introduced in a company owned backlight the white LED technology. This step opens the possibility to have access to the components in the display market. Instead of having a finalized display product which needs to be integrated in the head unit of a car we assemble the backlight, the glass, own electronics and the housing. A major advantage of this concept is the better control of the heat flow generated by the LEDs to the outer side because only a common housing is used for all the components. Also the requirement for slim products can be fulfilled. As always a new technology doesn't come with advantages only. An LED represents a point source compared to the well-known tube thus requiring a mixing zone for the multiple point sources when they enter a light guide. This zone can't be used in displays because of the lack of homogeneity. It's a design goal to minimize this zone which can be helped by the right choice of the LED in terms of slimness. A step ahead is the implementation of RGB LEDs because of their higher color rendering abilities. This allows for the control of the chromaticity point under temperature change but as a drawback needs a larger mixing zone.