This PDF file contains the front matter associated with SPIE Proceedings Volume 12906, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Micro-LEDs have the potential to create a generational change in display technology for the entire $160B display market. What is continuing to push out the broad adoption of Micro-LED across the display market is a missing “beachhead” market equivalent to the laptop market that began the decades long adoption of LCD across the entire display market. An AR glasses solution used as widely as vision correction glasses will fundamentally alter the way people interact with digital information and Mojo Vision believes AR glasses can be this “beachhead” market for Micro-LED. Mojo Vision is developing full Micro-LED displays based on GaN/Si blue LED + CMOS + Quantum dot color conversion. A development history will be given showing milestones, key technology process blocks and current status. A 300mm process fully compatible with GaN/Si wafers run in parallel with CMOS wafers in a standard 300mm CMOS fab is considered essential to reaching the Micro-LED display price point required for mass adoption. This paper will focus on development of a full wafer to wafer hybrid bonding flow for integration of CMOS to GaN/Si blue Micro-LEDs at 300mm done in collaboration with Applied Materials.

Micro-light-emitting-diode (MicroLED) display technology has drawn a lot of attention in display industry recently owing to the superior optical and electrical properties. Compared to conventional display technologies, MicroLED display demonstrates higher efficiencies, longer lifetime, much higher brightness, ultra-high pixel density, faster response time, and wider color gamut. In this work, the MicroLED display production technology and required achievement for commercialization is discussed. At the same time, MicroLED display for various applications are demonstrated.

Nanowire-based InGaN light-emitting diodes (nanoLEDs) have progressed to being the most efficient LEDs ever made at extremely small lateral sizes, and have the added benefits of highly directional emission and extremely narrow bandwidth. Augmented reality headsets and other A/R display applications will require displays that combine these properties with lowcost and high yield manufacturing.

Colloidal quantum dot (QD)-based light-emitting diodes (QLEDs) have achieved peak efficiency comparable to organic light-emitting diodes and are now poised for the development of full-color displays. Simultaneously, the potential of QLEDs is being explored for lasers, AR/VR, lighting, and industrial light sources demanding extended brightness. This study focuses on comprehensive strategies to enhance the brightness of QLEDs beyond the boundary of conventional display applications. Introduction of graded confinement potential into core/shell heterostructured QDs successfully mitigated nonradiative Auger recombination of charged or multiexcitons, often generated under high current density. A tailored top-emission device architecture on Si substrates enabled to extend the range of operational current over 10 A/cm2 . Our QLEDs achieved high brightness (>50 mW) comparable to class-3B lasers.

Quantum Dots (QDs) with it’s high photoluminescent quantum yield and absorption cross section have been established as a material of choice for color conversion applications. For a long time the industrial use of QDs has been restricted to a remote phosphor approach in liquid-crystal displays due to poor photothermal stability. While a lot of progress has been obtained for Cd-based QDs, the Cd-free alternatives are lagging behind. At QustomDot we have made a lot of progress towards obtaining photostable Cd-free QDs, currently surviving high blue light fluxes of 0,5-1,5 W/cm². We are presenting an overview of major challenges in developing QDs for microLED applications and main factors impacting the degradation mechanism of QDs under blue light illumination.

Metal-Organic Chemical Vapor Deposition (MOCVD) is today the preferred methodology for the epitaxial growth of AsP based semiconductor compounds which form the basis of multitude of optoelectronic devices. For high volume manufacturing (HVM) the epitaxy of these high-performance structures is required with high yield and low cost of ownership. In this paper, groundbreaking production technology developments based on the Planetary Reactor® technology will be introduced. Reactor geometry, in particular inlet geometry has been redesigned with the introduction of novel 4-fold injector, which proves to be a key component to enable the epitaxial growth on GaAs/Ge substrates up 200 mm, delivering in-wafer uniformities and precursor efficiencies comparable to those achieved on smaller substrate diameters. Full cassette-to-cassette wafer automation in combination with In-situ chamber clean delivers low defect levels and unmatchable reproducibility in addition to higher throughput. Uniformity, tunability and reproducibility results will be thus presented for two prototypical case scenarios: VCSEL on Ge and Micro LED on GaAs to corroborate Reactor flexibility in meeting industry requirements for next device generation.

Light-emitting diode (LED) photonics is a rapidly growing field that has applications in various domains, such as communication, lighting, display, and sensing. However, the fabrication and characterization of LED photonic devices pose several challenges that need to be addressed. Compared to the silicon semiconductor industry, LED devices are based on exotic substrates, such as sapphire (AlO), silicon carbide (SiC) and gallium arsenide (GaAs). One of the challenges in semiconductor process integration development and production control is checking the process quality through characterizing and analyzing defects at different process steps. Typically, wafers at different process steps are sent to the failure analysis laboratory (FA lab) for detailed analysis by transmission electron microscope (TEM), energydispersive X-ray spectroscopy (EDX), cross scanning electron microscope (XSEM), or gallium focus ion beam (GaFIB). These methods are destructive, slow, and expensive. As a result, having a non-destructive, fast, and low-cost method for full-wafer analysis can help speed up the integration cycle and improve process control and yield. This paper is a collaboration between ams-OSRAM international GmbH and Applied Materials Inc. The paper describes the benefits of inline Xenon Plasma FIB (XePFIB) and SEM in the fab for improving the cycle time of root cause analysis and process integration development. It explains the methods that are used to solve the problems of handling and analyzing special substrates, like transparent sapphire wafers in semiconductor manufacturing for LED and photonic products. Specifically, the paper describes the methodologies that are used to optimize the SEM image resolution and XePFIB cross-section quality by reducing the charging effects of the sapphire dielectric substrate.

Advances in single-photon sources have proved pivotal to the progress of quantum information processing and secure communication systems. This study addresses the imperative need for developing commercially viable, electrically-driven single-photon sources capable of operating at or above room temperature with rapid response times and emission in the telecom wavelength range of 1260 to 1675 nm. We introduce an innovative single-photon light-emitting diode (SPLED) design employing GaAs quantum dots (QDs) and self-assembled GaSb quantum rings (QRs). The core of our design is an electron filter layer composed of GaAs QDs embedded in Al_xGa_1-xAs, engineered to inject (single) electrons into an ensemble of type-II GaSb QRs in GaAs, where they recombine with strongly confined holes producing (single) photons at a wavelength governed by an optical cavity created using distributed Bragg reflectors (DBRs). This concept removes the need to select individual QD emitters, rendering the device highly suitable for scalable production. Our research demonstrates a comprehensive theoretical and experimental analysis using nextnano++ simulations and fabricated prototype device characteristics. Quite remarkably, we find that the emission properties of the SPLED devices actually improves as operational temperature is increased from 20 °C to 80 °C, making them attractive as practical devices.

This paper presents a novel approach to enhance the performance of Quantum dot (QD) based light-emitting diodes (LEDs) by incorporating Bragg resonator substrates. By depositing QD-LED layer stacks on tailored Bragg resonator substrates, the emission spectrum of red-emitting QD-LEDs is narrowed to less than 20 nm, and the emission pattern becomes more directional. Additionally, the modulation characteristics of QD-LEDs on Bragg-substrates are investigated. These findings demonstrate the potential to improve the usability of QD-LEDs in displays, lighting, and sensing applications.

The use of ultraviolet (UV-C) light for disinfection has been a well-established practice for many years. In recent years, the development of UV-C LED technology has provided a promising alternative to traditional low pressure mercury lamps. One of the most anticipated parameters of UV-C LED technology is the external quantum or wall plug efficiency. This paper reviews the recent progress and prospects of UV-C LED development, focusing on wall plug efficiency and lifetime at different wavelengths which are suitable for germicidal applications. The robustness of UV-C LED packages is also improving significantly and even tests according to the automotive AEC Q102 specification have been passed successfully. Beyond the pure LED parameters there are further factors and features that affect the system efficiency of UV-C LED based disinfection devices. Examples are demonstrating the big differences in system efficiency between conventional lamp and LED based systems. The big steps in development of UV-C LED during the last years justifies an optimistic outlook to target a replacement of conventional low pressure mercury lamps in the coming years.

UVC LEDs are of fundamental importance for many applications, including sterilization and disinfection, thanks to their high efficiency and low environmental impact. However, several physical processes still limit the lifetime and reliability of these devices. We present recent case studies in the field of UVC LED reliability. Initially, we review the performance/efficiency of state-of-the-art commercial devices, and discuss the issues related to LED self-heating, and the related electro-optical transient behavior. Then, we discuss the impact of defects on LED degradation, based on combined deep-level transient spectroscopy (DLTS) and deep-level optical spectroscopy (DLOS) measurements, and Technology Computer-Aided Design (TCAD) simulations. We show that, during prolonged operation, UVC LEDs can show considerable changes in the electrical characteristics: a) an increase in the sub-turn on leakage, that can be reproduced by TCAD as due to an increase in trap-assisted tunneling, related to deep traps located in the interlayer between the last barrier and the EBL; b) an increase in the turn-on voltage, that is explained by the degradation of the metal/p-GaN contact, due to a decrease in the active magnesium concentration. Electro-optical measurements reveal that a stronger degradation is detected at low measuring current levels, confirming an important role of defect-mediated recombination. Remarkably, degradation kinetics do not follow an exponential trend, but can be fitted by using the Hill’s formula. A higher Mg doping in the EBL mitigates the degradation rate. Results are interpreted by considering that degradation is due to the de-hydrogenation of point defects, which increases the density of non-radiative recombination centers.

While firstly described already in 1953 by Juza et al., the substance class of lithium oxonitridosilicates grew very slowly over the past 70 years with only one new compound every twenty years on average. This changed only recently, since we were able to synthesize three new representatives, two of them with interesting luminescence properties. Based on these findings, we set up a scheme for classification of the known members of the substance class, which at the same time might offer the possibility to predict potentially stable yet unknown compounds. The results are of interest, not only structurally but also from the perspective of luminescent materials, since no rare earth, alkaline earth or even heavy alkali metal is present in the structures providing the obvious site for doping with Eu(II).

We present the results of accelerated lifetime tests conducted on UV-C LEDs with nominal wavelengths between 265 and 275 nm. We aged the devices at their absolute maximum current, performing electrical, optical, and spectral characterizations. Reliability tests showed L90 above 300 h and L80 above 1000 h, and we identified common behaviors, such as an optical recovery during their operation, and an instantaneous OP decrease at the turn-on. To conclude, we correlated the total optical power emitted with the number of disinfection cycles that the device could provide to reach log3 inactivation of the Sars-CoV-2 virus.

We have developed Direct Optical Wiring (DOW) technology and successfully implemented it in chip-to-chip optical links in the form of commercially available products. The chip-to-chip optical coupling efficiencies using the DOWbased optical links exceed 93% in both in-plane and out-of-plane optical system, where the in-plane optical link includes vertical-cavity surface-emitting lasers (VCSELs) and photodiodes (PDs); and the out-of-plane one directly connects an edge-emitting laser diode to a PD. Such outstanding optical coupling is attributed to the minimized optical reflection and/or scattering in the end-to-end optical link, resulting in an improved bit error rate (BER). LESSENGERS® 800G QSFP-DD SR8 and 400G QSFP112 SR4 optical transceiver modules featuring DOW technology demonstrate the BER of ~ 5 × 10^-10 even at an elevated device temperature of 57°C.

Increasing the number of active regions is an effective approach for scaling optical output power in vertical cavity surface emitting lasers (VCSELs). This, in addition to high power conversion efficiency, miniaturized packaging, addressability, fast pulse rise time, and minimal spectral shift with temperature, make multijunction VCSELs an attractive alternative to conventional edge-emitting lasers (EELs) for variety of automotive, industrial, and consumer markets. Especially, LiDAR applications using Time of Flight (ToF) mapping methods require power efficient VCSELs with high throughput and fast rise times for achieving high spatial resolution and longer detectable ranges. However, with greater available optical gain in multijunction VCSELs, comes a more complex cavity structure which includes multiple active regions, tunnel junctions, and optical confinement layers. These can interconnectedly affect the optical, spectral, and electrical characteristics of these devices. For example, wider far-field beam divergence angle for multijunction VCSELs than those of the single-junction structure has been observed, which could be due to structural design parameters, in addition to device processing variability. This can severely reduce the usable output power from these devices, which is typically defined to be enclosed within certain angular limits. In this paper, we will demonstrate the recent advances in the development of high power multijunction VCSELs with up to eight active junctions, lasing in the wavelength range of 850-940nm. Both continuous-wave and short pulse characteristics of these devices measured at room temperature and wider temperature range show their reliable performance and demonstrate their suitability for integration in variety of LiDAR and other high-power sensing applications.

While most of the efforts in the development of vehicle headlamps are focused on the design of high-resolution visible beam distributions, recent research shows the possibilities of using a near-infrared auxiliary headlamp for machine vision. Contrary to previous non-imaging approaches not designed to attenuate parts of the beam, this feature can supplement missing light during low-beam driving. This paper aims to evaluate various emitters and optical concepts for an auxiliary near-infrared headlamp, with particular emphasis on etendue and power density. Firstly, the system requirements for an automotive headlamp consisting of a visible and near-infrared source are discussed. Secondly, we evaluate differnent design approaches to the optical system with focus on the near-infrared subsystem. Consequently, the optomechatronical system is discussed, looking at optics, electronics and mechanics seperately.

In this paper, we report the latest advances in light-emitting diodes (LEDs) of the three primary colors red, blue, and green optimized for ultra high-power operation to achieve highest luminance and radiance values. These kinds of LEDs are mainly used in étendue-limited applications, particularly projectors. For the three colors different material systems are used: AlInGaP for red and InGaN for blue and green, while green uses a blue chip combined with a green ceramic converter. The chip designs and epitaxies have been modified compared to lower power versions to withstand high current densities up 6.6 A/mm² for blue, up to 4.5 A/mm² for red. The LED chips have been optimized at this operating point. The latest improvements show an increase of 8% in luminance for red, 17% for green, and 15% in radiance for blue compared to the previous generation. The LEDs using the latest improvement measures are setting the benchmark for ultra high-power LED technology.

The integration of transition metal chalcogenides, such as MoS₂, with III-V compound semiconductors has posed significant challenges in the implementation of two-dimensional materials in optoelectronics applications. In this presentation, we propose a breakthrough method for directly growing molybdenum disulfide (MoS₂) on III-V compound semiconductors, compatible with a batch microfabrication process. By synthesizing a thin film of MoS2 on a gallium- nitride-based epitaxial wafer, we successfully developed a thin film transistor array. In addition, we achieved seamless monolithic integration of the MoS₂ thin film transistor with micro-light-emitting-diode (micro-LED) devices, resulting in a state-of-the-art active-matrix micro-LED display. This novel approach paves the way for promising heterogeneous integration, combining established semiconductor technology with emerging two-dimensional materials, ultimately enabling high-performance optoelectronic systems.

We have investigated the use of segmented red, green, and blue LED emitters for use in LCoS projection systems. We find that segmenting the light emitting area has a minimal impact to the efficacy and wall plug efficiency of the die thus validating that these devices could help in significantly reducing the power consumption of LCoS systems by enabling local dimming strategies.

To ensure appropriate quality control during marketing, accurate assessment of sugar content in citrus fruits is essential. Additionally, it is important to limit sugar intake of people with medical conditions. In this study, we present a simplified and accurate approach for measuring sucrose content in Valencia oranges by using a low-cost optoelectronic system that we designed and fabricated. The proposed system comprises a plastic optical fiber (POF) integrated with a multispectral sensor for obtaining the visible spectrum of citrus juices. This integration enabled the detection of absorption changes in the evanescent field of the POF when contacted with the juice samples. The multispectral sensor digitally records the response, capturing wavelengths from 415–910 nm. The collected data are further processed and analyzed using an information management system. By incorporating these optical and electronic components, a compact and affordable automated instrument was fabricated that can potentially replace conventional laboratory equipment for determining the Brix sugar content of fruits.

Optical wireless power transmission (OWPT) has emerged as a promising technology for remote power applications due to its long-distance transmission, high directionality, and lack of electromagnetic interference. In practical applications, light-emitting diode (LED) based OWPT systems have advantages over Laser Diode in terms of easy commercialization and reduced safety issues. In this research, we propose a deep learning-based approach to optimize the irradiation spot for improving the LED-OWPT transmission distance. A novel configuration consisting of three-layer lenses and a depth camera minimizes the spot size by real-time detecting the transmission distance. The system achieves an auto-focus performance, resulting in an 8-times improvement of the effective surface irradiation at 3m on a 5×5cm² receiver.

This paper presents a method for supporting wayfinding in crowded buildings using Visible Light Communication (VLC). Luminaires are repurposed to transmit encoded messages, providing location-based information to users. Tetra chromatic LEDs and OOK modulation efficiently transmit data, while error detection techniques ensure reliable transmission. Users carry receivers that interpret the light signals and perform localization calculations. Wayfinding algorithms guide users with turn-by-turn directions, landmarks, and alerts. The system integrates VLC into an edge/fog architecture, utilizing existing lighting infrastructure for efficient data processing and communication. It enables indoor navigation without GPS, demonstrating self-localization and optimizing routes. This method enhances accessibility and convenience in unfamiliar buildings.

This study addresses the challenges and research gaps in traffic monitoring and control, as well as traffic simulation, by proposing an integrated approach that utilizes Visible Light Communication (VLC) to optimize traffic signals and vehicle trajectory at urban intersections. The feasibility of implementing Vehicle-to-Vehicle (V2V) VLC in adaptive traffic control systems is examined through experimental results. Environmental conditions and their impact on real-world implementation are discussed. The system utilizes modulated light to transmit information between connected vehicles (CVs) and infrastructure, such as street lamps and traffic signals. Cooperative CVs exchange position and speed information via V2V communication within the control zone, enabling flexibility and adaptation to different traffic movements during signal phases. A Reinforcement Learning, coupled with the Simulation of Urban Mobility (SUMO) agent-based simulator, is employed to find the best policies to control traffic lights. The simulation scenario was adapted from a real-world environment in Lisbon, and it considers the presence of roads that impact the traffic flow at two connected intersections. A deep reinforcement learning algorithm dynamically control traffic flows by minimizing bottlenecks during rush hour through V2V and Vehicle-to-Infrastructure (V2I) communications. Queue/request/response interactions are facilitated using VLC mechanisms and relative pose concepts. The system is integrated into an edge-cloud architecture, enabling daily analysis of collected information in upper layers for a fast and adaptive response to local traffic conditions. Comparative analysis reveals the benefits of the proposed approach in terms of throughput, delay, and vehicle stops, uncovering optimal patterns for signals and trajectory optimization. Separate training and test sets allow monitoring and evaluating our model.

LiDAR technology plays a vital role in various applications, including autonomous driving, environmental monitoring, and robotics. Accurate target detection is a crucial task in LiDAR systems to ensure the precise identification of objects and obstacles. However, the absence of clear standards for LiDAR system design parameters poses challenges in determining the optical system configurations. This paper focuses on a procedure that determines the necessary resolutions in LiDAR systems, with a specific emphasis on target detection algorithms. The investigation methodology encompassed the steps involved in scenario generation, capturing LiDAR point cloud data, and evaluating the obtained LiDAR data. Multiple widely-used algorithms are selected to represent diverse approaches to object detection. The paper concludes by summarizing the derived angular resolution requirements for each algorithm. By incorporating these findings, developers can optimize LiDAR system configurations to meet the specific demands of their application domains, ultimately enhancing the performance and reliability of LiDAR applications.

Interband cascade lasers (ICLs) are highly efficient semiconductor lasers operating in the mid-infrared range. Their cascade structure of multiple quantum wells enables continuous operation at room temperature with low threshold current. This study explores the impact of tensile and compressive strain on W-QWs' electronic structure and carrier dynamics. Using transient absorption measurements on specific material structures, researchers investigated carrier lifetimes and fundamental transitions. Photoreflectance and photoluminescence measurements were also employed to study band structure and optical properties. The findings provide insights into optimizing ICL performance, improving their performance in application for gas sensing, spectroscopy, medical diagnostics, and communication.

In recent years, distance measurement technology has advanced with the development of electronic devices, contributing to various industries. LIDAR, which stands for Light Detection and Ranging, uses laser light to detect reflections from objects and measure their distance. Typically, these distance measurement devices can accurately measure objects that are only a few centimeters away, while some products can measure distances as long as several meters. However, if either the displacement sensor or the object itself remains stationary, it is not possible to detect the surface shape of the object, including its tilt or unevenness. This research focuses on developing a measurement device that can accurately measure the distance to an object, even when the object has low surface contrast. The device is capable of measuring both the inclination and distance of an object at distances of several meters.

We report on progress in the realization of Field Emission Devices (FED) with AlN-based anodes emitting in the spectral window of 200-230nm for persistent disinfection of air and surfaces in the presence of humans. Modeling, experimental studies, and trade-offs between sputter deposition and MOVPE grown AlN anode films and GaN/AlN multiple quantum wells (MQW) indicate the feasibility of 1’’-size FED emitting at 225 nm wavelength with 1 mW power, capable to quickly deactivate the SARS-CoV-2 virus.

High-power white LEDs for outdoor lighting were submitted to accelerated lifetime stresses to evaluate their robustness and reliability. LEDs featured a 2 mm2 chip with 2 A absolute maximum current (I_abs) at 135 °C junction temperature. A first high-temperature, high-current robustness stress was performed at 1, 1.2, 1.4, 1.6 times Iabs for 50 hours. This stress caused a heavy decrease of optical power and a degradation of colorimetric properties of the LEDs stressed at currents exceeding I_abs. Optical analysis showed darkening of the phosphors and silicone and cracking of the lens. A second, long-term, stress was performed at 0.8 times I_abs at 45, 65, 85, 105 °C. This stress showed almost no lowering in flux for the samples stress at 45 and 65 °C, whereas samples stressed at 85 and 105 °C showed a decrease in flux from 2500 and 200 hours of stress, respectively, estimating a L90 lifetime of 5500 and 1500 hours. xy coordinates shifted proportionally to stress temperature. LEDs stressed at 85 °C and 105 °C eventually failed catastrophically, similarly to the high-current stress, with silicone and phosphors darkening and lens cracking. Raman analysis on high-current stressed LED lenses showed that poly(methyl,phenyl)siloxane was used as lens material. Stress induces higher luminescence of the silicone under Raman analysis. The cause of degradation is attributed to thermomechanical stress (cracking) and high-temperature silicone decomposition (darkening), possibly due to phosphors thermal quenching, causing a hot-spot just above the chip (confirmed by thermography), even if the junction temperature was within manufacturer specifications.

MicroLEDs are projected to have triple-digit growth over the next five years and will have significant benefits for new and existing display applications. MicroLEDs will see high demand in applications such as smartwatches, mobile devices, AR/VR, automotive and TVs. Critical in the manufacturing of these devices is MOCVD epitaxial growth technology. This technology must meet industry’s high-performance requirements, including extremely uniform wavelength, thickness and composition, dopant control and low defectivity while reducing costs via high productivity, high yields and lower operating expenses. These requirements must also be met over the whole wafer as well as across the transfer field. Veeco has developed the Lumina™ As/P MOCVD for Red MicroLEDs that meet and exceed industry’s roadmap on 8” substrates. Details of the technology and data will be discussed as part of this presentation.