Display Technology
Advanced epitaxy to solve microLED production challenges
By Dr. Rodney Pelzel, CTO of IQE plc A
s consumer devices become smaller and more capable, Original Equipment Manufacturers (OEMs) must incorporate
additional functionality while minimizing power consumption so that battery life is adequate. One of the main focus areas is display technology, with buyers looking for bright, ultrahigh-resolution screens that make interacting with their gadgets more effective and enjoyable. However, screens typically consume the most battery power, especially in smartphones, and this is driving the need for extremely small, highly effi cient microLEDs. MicroLEDs have been shown to offer multiple advantages over both LCD and OLED technologies, and devices with excellent contrast and brightness with fast response times and adequate effi ciency have been demonstrated. In addition, microLEDs have a substantially longer lifetime than OLEDs. However, incorporating microLEDs into a full colour display is extremely complex, which has limited their commercialization. The market need has driven signifi cant R&D investment in microLED technology over the past few years and further investment is needed to address fundamental challenges before three colour microLED displays are a commercially viable, volume product. Market analyst fi rm Yole Intelligence estimates that the industry has spent $11 billion on microLED
development so far, with this fi gure predicted to rise to $18 billion by 2025. The fi rst high- volume application is predicted to go into production as soon as 2024, with smartphones likely driving the growth of microLED sales. So how will microLEDs reach mainstream adoption? What is needed for production to overcome the technical hurdles?
Compound semiconductors, such as gallium nitride (GaN) and gallium arsenide (GaAs), will be the basis for microLEDs, just like they underpin the commodity LED market today. However, the materials requirements for
microLEDs will be more demanding as size reduces. For example, effi ciency becomes a challenge for small devices. In addition to the materials challenges, there are signifi cant manufacturing obstacles to scaling volume. For example, pick and place needed to create a RGB pixel from three separate smaller red, blue and green emitters likely becomes untenable at very small sizes and very large displays. Addressing this fundamental scaling challenge requires engineering at the fundamental materials level using epitaxy – the process of making the semiconductor wafers that is controlled on the atomic level.
Epitaxy is a specialist task, and working with expert providers is the best way for microLED component vendors to meet their needs for this technology. For instance, IQE has provided such custom epitaxy solutions for 30+ years and has a proven track record of scaling complex technology for high volume manufacture on large diameter (200mm and 300mm) substrates. Through its key partnerships with companies like Porotech and MICLEDI, IQE is establishing both GaN- and GaAs-based technologies for microLEDs and thereby enabling product insertion across multiple markets and applications. IQE is developing 200mm (8-inch) single
20 May 2023 Components in Electronics
colour wafers for AR applications and has a roadmap to 300mm (12-inch). Being compatible with leading edge 200mm and 300mm silicon foundries, enables high volume manufacture that is needed for the wafer quantities required by the AR market. Three colour applications provide an excellent example of how fundamental epitaxy engineering at the atomic scale allows broad product adoption. Using pick-and-place RGB technology for larger displays (anything bigger than a wearable or mobile handset screen) provides scaling challenges. This problem disappears if all three colours (RGB) are created in a single material, GaN (vs. B and G in GaN and R in GaAs). The GaN- only approach means that scaling to small dimensions is achieved by an appropriately designed Si-based backplane wafer. In this scenario, mainstream CMOS technology capable of defi ning features down to the nm scale is leveraged. With such a development, there would be immediate line of sight to capability required for ultrahigh resolution large format displays.
MicroLEDs represent the next generation of immersive display technologies, and their market is projected to experience multi- billion-dollar growth across a diverse range of customer sectors, including consumer electronics. These tiny, high-brightness microLED pixels hold enormous potential for a wide array of applications such as AR/MR/ VR, the metaverse, wearable devices, smart displays, and large-scale direct view displays. To achieve the scale required for microLEDs, compound semiconductors are an essential enabler, and IQE’s innovative epitaxial growth technologies and mass production capabilities are tailored for manufacturing them. Although full commercialization is not yet a reality, vendors are already ramping up their production processes and driving down costs. Before we know it, microLEDs will become ubiquitous and low-cost, and IQE is at the forefront of bringing compound semiconductor-based microLED displays to the mass market.
www.iqep.com
www.cieonline.co.uk.uk
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