AR-Vµ™ is the ultimate microLED display for AR/MR applications. An HD, RGB active-matrix display, with fine pitch and high pixel yield, using Plessey’s proprietary GaN-on-Silicon (GaN-on-Si) monolithic microLEDs, uniquely bonded to a high-performance CMOS backplane.
Plessey’s first active-matrix demonstration was a 0.7″ diagonal display chip with 8-micron pitch and 6-micron emitters. Specifications of the display include:
• Resolution: Full HD (1920×1080 pixel) with the future capability of 4K ultra-HD
• Refresh rate – 120 Hz
• 99.9% yield and excellent uniformity due to proprietary GaN-on-Si and strain engineered process.
• 60 frames per second (fps)
• 10% of the power of current LCDs
• Five to 10 times higher brightness than OLEDs
Plessey can manufacture native Blue, Green and Red InGaN material or tune wavelengths from 400 – 650 nm using its GaN-on-Si platform. Plessey’s proprietary GaN-on-Si naturally emits a Blue light and previously used the native Blue as a base for quantum dot colour conversion before developing native Green and Red in 2019.
With no colour conversion losses, the native Green emission is an order of magnitude brighter than the colour converted process for microLEDs. With a dominant Green wavelength of 530nm and a full width half maximum wavelength (FWHMW) of 31nm, the native Green is well suited for full-colour displays; compared to over 40nm for QD converted green colour converted Green.
Plessey’s InGaN Red microLEDs have a wavelength of 630 nm at 10 A/cm2, FWHMW of 50 nm, a hot/cold factor over 90% and higher efficiencies over conventional AlInGaP and colour converted Red at ultra-fine pixel pitches.
Following a continued partnership with Jasper Display Corp (JDC) including extensive capital investment in a complete toolset, enabling successful wafer to wafer bonding. Plessey has succeeded in wafer-level bonding of its GaN-on-Si monolithic microLED wafers with JDC’s eSP70 silicon patented backplane technology, resulting in microLED displays that contain addressable LEDs.
Wafer-level bonding poses significant technical challenges and has not been previously achieved between a GaN-on-silicon LED wafers and high-density CMOS backplanes.
Plessey initially achieved the world’s first mechanically successful wafer to wafer bond in early April 2019. This significant success has now been followed by a fully functional, electrical and mechanical bond, resulting in a fully operational microLED display.
The first display demo included current-driven monochrome pixels on a pitch of 8-micron. Each display requires more than two million individual electrical bonds to connect the microLED pixels to the controlling backplane. The JDC backplane provides independent 10-bit single colour control of each pixel. Bonding a complete LED wafer to a CMOS backplane wafer incorporates over 100 million micro-level bonds between the wafers.
In January 2020, Plessey has further optimised their processes to achieve a successful wafer to wafer bond of a monochrome native Green 1080p microLED display (0.26” diagonal) to a 3-micron pixel-pitch backplane from Compound Photonics (CP), creating over two million individual electrical bonds.
CP and Plessey engineering teams have also successfully fabricated functional microLED display modules combining CP’s industry-leading high speed digital low-latency display backplane with Plessey’s breakthrough GaN-on-Silicon monolithic microLED array technology. Plessey’s team produced the microLED array wafer bonded to CP’s backplane wafer at its Plymouth, UK, facility. In turn, CP’s team assembled and packaged display modules from the bonded wafer pair at its Phoenix, AZ, USA, facility. Both teams are currently performing initial characterization work at CP’s Vancouver, WA, USA, facility.
Initial samples of the 0.26 inch diagonal, Full HD 1080p resolution microLED display modules integrated with display driver IC and MIPI input are expected to be available by summer of 2020.
Plessey delivers platforms that provide OEM’s and product developers with a solution to retrofit current products or develop new concept designs, around a compact, flexible and highly efficient microLED display.
Due to the small form factor, they can be easily integrated into smart glasses, and head-mounted displays for navigation, sport & leisure, and optical instruments. We also work closely with our customers and R&D projects to ensure easy integration and we can provide plug and play ready solutions with a range of protocols.
The silicon substrates’ thermal conductivity means heat can be dissipated from the system much more quickly compared to the widely used sapphire substrate. As a result, GaN-on-Si LEDs are more reliable and reduce both the cost of heatsinking and the space this takes up.
This also results in 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. All our enabling technologies put us in a pole position to deliver the first microLED AR products that are of a high standard and have outstanding performance.
MicroLED is the first brand new display technology to be commercialised in more than a decade, demand for microLEDs is accelerating. With research consultancy Yole Développement forecasting the market could reach up to 330 million units by 2025.
Plessey’s IP protected GaN-on-Si is recognised as the only technology platform capable of addressing all the challenges involved with manufacturing microLED displays in high volumes, cost-effectively., Building on its technological IP, expertise and many years of experience in the high-power LED lighting market and production of CMOS image sensors, Plessey has developed an advanced gallium nitride (GaN)-on-silicon (Si) technology platform. This platform is now enabling innovations for the manufacture of microLEDs that will, in turn, be available to the emerging developers of disruptive microLED display and micro-display applications.
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 and multiple chips on 150, 200 and soon to be 300mm wafers. This unique approach brings several key advantages and solves the issues that have held back microLEDs from the mass market until now.
MicroLEDs offer an emissive display technology that delivers high contrast, high speed, and wider viewing angles. MicroLEDs also offer the potential for significantly higher brightness and will offer this at greater efficiency thus enabling power trade-offs, as well as enhanced robustness and longer lifetimes. They can also provide for a smaller form factor, key for numerous applications, for example, head-mounted displays, in contrast to reflective technologies that require a separate light source and complex and costly optics.