Monolithic microLED displays less than six months away: Plessey

Plessey Semiconductor, a developer of optoelectronic technology solutions, has committed to being the first to market with a monolithic microLED-based display based on GaN-on-Silicon, with launch expected within the next six months.

Plessey has also commenced an extensive licensing program that will see the company license out its GaN-on-Silicon expertise to microLED manufacturers in line with its new business strategy of becoming the photonic industry’s foremost technology platform provider.

MicroLEDs are emerging as the only technology that can provide high luminance in a small format, with leading suppliers of wearable technologies currently pursuing manufacturers that can deliver an ideal microLED solution. Demand for microLED displays is thus accelerating, with research consultancy Yole Développement forecasting the market could reach up to 330 million units by 2025.

Now, Plessey intends to be the first to manufacture a monolithic display based on microLEDs fabricated using a GaN-on-Silicon approach. GaN-on-Silicon is said to be the only technology platform capable of addressing all of the challenges involved with manufacturing microLED displays in high volumes and cost-effectively.

“By being the first to market with a monolithic microLED display, we will be demonstrating our expertise and the ability to access our proven turnkey solution, enabling manufacturers to ramp up the development and production of microLED displays,” said Plessey CEO Michael LeGoff.

One of the challenges involved with manufacturing microLED displays using a non-monolithic approach is the placement of LED chips onto a CMOS backplane, currently achieved using pick-and-place equipment. This involves the individual placement of every LED on a pitch of less than 50 μm, requiring new and expensive equipment that is subject to productivity issues. As the pixel density of displays increases and pitch reduces, pick and place becomes less feasible both commercially and technically.

Moving to a monolithic process removes the need for chip placement and will enable smaller and higher resolution displays for a range of applications, including virtual reality (VR), augmented reality (AR) and head-up displays (HUDs). Plessey’s monolithic technology doesn’t require pick-and-place equipment and isn’t subject to the associated productivity issues.

A fully monolithic approach also supports the integration of the standard CMOS circuitry necessary for driving microLED displays, as well as the close integration of high-performance graphic processing units (GPUs), all of which can be carried out using standard CMOS manufacturing methods. By solving all of the major challenges, licensees gain instant access to a technology platform that is ready for volume production.

“Monolithic microLED technology is the only viable solution that can enable products that are not only compact enough to be worn without restricting the overall experience for AR and VR applications and in HUDs, but also provide the size, weight, power and luminance needed,” said Plessey CTO Dr Keith Strickland.

Plessey demonstrated its monolithic microLED technology at CES 2018, revealing how the technology can enable new AR and VR applications by delivering the next generation of HUDs. Produced in collaboration with Artemis Optical, the demonstrator confirmed that Plessey is ready to enable its partners to move into production of a monolithic display based on microLEDs using the GaN-on-Silicon approach.

“GaN-on-Silicon is the only technology that makes sense in terms of scalability and performance,” said Dr Strickland. “It offers better thermal conductivity than sapphire and higher luminosity than OLED, which is why this technology is widely acknowledged to be the only one that can deliver high-resolution, high-luminance displays.”

The demonstrator combines Plessey’s monolithic display, based on an array of microLEDs integrated alongside an active matrix backplane, with film technology and a single lens arrangement from Artemis. The combination of technologies removes ambient light in the wavelength matching the microLED display output, resulting in a HUD that delivers very high display brightness with low power consumption, in a format that is considerably smaller than existing HUD designs.