Plessey’s IP protected MOCVD based GaN-on-Silicon monolithic microLED display technology is set to disrupt the display market and make possible a new generation of augmented reality devices and display solutions. It is a globally acknowledged as a platform for fully emissive monolithic microLED displays

TECHNOLOGY OVERVIEW

At the start of 2018, Plessey announced its capability to produce microLEDs (microscopic light-emitting diode) based on its proprietary GaN-on-Silicon LED production technology, which solves the problems of manufacturing such tiny LEDs.

There is a huge opportunity for microLEDs to replace incumbent LCD and OLED technologies in a wide range of display applications, from HDTVs to smartphones, smart watches, HUDs, and AR headsets. However, challenges remain before that potential can be fully realised.

Plessey’s core focus is the provision of innovative illuminators for display engines (DMD and LCOS) and full-field emissive microLED displays that combine very high-density RGB pixel arrays with high-performance CMOS backplanes to produce very high-brightness, low-power and high-frame-rate image sources for head-mounted displays (HMDs), and augmented and mixed reality (AR/MR) systems.

Until now, manufacturing microLEDs has not been easy partly because they’re so small that today’s pick-and-place technology is not accurate enough. That’s where Plessey’s proprietary technology comes in. Plessey’s LEDs are made from gallium nitride on a substrate of silicon (GaN-on-Si), instead of the usual sapphire. This enables the creation of monolithic microLEDs with multiple emitters on a single chip. This unique approach brings several key advantages and solves the issues that have held back microLEDs from the mass market until now.

This means greater lumen output, increased energy efficiency, higher resolution and better contrast. It’s also more cost-effective to produce than competing LED technologies. The technique can easily be scaled to 200mm wafers and larger, improving cost and yield, and circumventing the shortcomings of traditional pick-and-place.

INNOVATIVE AND PRODBLEM SOLVING TECHNOLOGY

One of the main challenges of manufacturing microLEDs is their placement on a substrate, which is currently achieved using pick-and-place equipment. This involves the individual placement of every LED on a pitch of less than 50 microns, which requires new and expensive equipment that is subject to productivity issues.

As the pixel density of displays increases and the LED pitch becomes ever smaller, pick-and-place becomes less feasible both commercially and technically. The development of massively parallel processing equipment offers hope, with the ability to simultaneously pick up hundreds or even thousands of LEDs from a wafer and then attach them to a backplane, but clearly this would require significant capital expenditure from companies.

For example: Smartphones and smart watches might typically offer 400ppi pixels per inch (PPI) displays, based on an 80-micron pixel pitch. But moving to AR applications means the pixel pitch needs to be reduced to 40 microns, or even as low as 10 microns. It is beyond the ability of pick-and-place machinery to place pixels with any kind of accuracy at this scale.

Because it doesn’t require pick-and-place equipment, Plessey’s monolithic microLED technology overcomes the productivity issues related to wafer bonding. Displays require microLEDs to interface to a backplane, and while bonding individual LEDs to a backplane has been shown to be technically viable, it is questionable whether it is commercially viable to scale it down to smaller displays. By contrast, Plessey’s monolithic solution enables all the microLEDs to be bonded to an active matrix backplane in a single process and is largely independent of wafer size.

These advantages are unique to Plessey, which has the only commercially available monolithic microLED solution. Plessey’s microLED solution harnesses its unique technology to allow our partners such as Vuzix to create ground-breaking AR products.

Moving to a monolithic process will enable smaller and higher-resolution displays for a range of applications and Plessey’s GaN-on-silicon is the only technology that can deliver the required levels of scalability and performance. It offers higher luminosity than OLED and also better thermal conductivity than sapphire, and is becoming widely acknowledged as the best bet to deliver the next generation of high-resolution and high-luminance displays.

AR devices and other wearables need to be as small and light as possible, which means they need to run on as little power as possible. Using an integrated monolithic array of RGB pixels with advanced first-level micro-optical elements to create a bright, collimated and highly uniform light source, Plessey has developed an optical system that is up to 50% smaller, lighter, simpler and cheaper than existing solutions. It’s significantly more efficient, too, thanks to high-performance microLED emitters and minimal optical system losses.

OUTCOMES AND SUCCESSES

Plessey’s microLED technology is already making its way into the AR devices of the future. In June 2018 Vuzix, one of the world’s leading developers of smart glasses and video wearable devices, announced it will be using Plessey’s microLED technology in the development of its next-generation AR glasses. In fact, the market opportunity for microLEDs is nothing short of staggering. MicroLED forecasting report by n-tech Research projects the overall market opportunities for MicroLED technology to grow from $0.5B to $22. 4B by 2024.

Plessey has also demonstrated the potential of microLEDs elsewhere, with the development of 100- and 20-micron pitch LED arrays for a print-head project with LumeJet, based on blue microLEDs and offering a density of 400 pixels per inch (ppi). Since Q3 2018, Plessey has announced several manufacturing partnerships with key industry technology partners including: Jasper Display, AIXTRON SE (FSE: AIXA), EV Group and most recently Nanoco Technologies with many more announcements being released in 2019.

By overcoming the difficulties of manufacturing microLEDs on a commercial scale, Plessey is playing a central role in making microLEDs a mass-market product. Plessey is actively engaging with partners (Jasper/ AIXTRON/ Vuzix) to create exciting new products based on its production-ready microLED technology platform with other partnerships being announced soon. Plessey’s microLED technology was also recently named as a CES 2019 Innovation Awards honoree in the ‘Embedded Technologies’ category ahead of its participation at CES in January 2019, the global stage where next-generation innovations are introduced to the consumer marketplace.

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