Red microLED breakthrough for AR displays
Porotech red InGaN 960×540 pixel display (courtesy Poro Technologies Limited)

Autumn is a time of year that the folk at Porotech in Cambridge, UK seem to love. Those deep red autumn colours mark a year of significant growth. This time last year Porotech announced they could fabricate wafer-scale red emitting nano-porous InGaN, suitable for microLEDs.

This autumn Porotech are announcing a ‘world first’ red microLED display based on InGaN. Red microLED display devices based on InGaN are a game-changer for AR (augmented reality) and VR (virtual reality) display devices. Why?

All video display devices are based on composite red, green and blue light signals which the human eye recognises as a millions of different colours. To achieve this pc monitors, televisions and digital projectors use red, green and blue light sources. A variety of different LED choices are available for each of these colours however until recently their light emitting materials had quite different compositions. For large panel displays this is not a huge problem, individual LEDs can be picked and placed together by machine. Tiny display devices used in AR are much more demanding.

For smart glasses, the display device must be less than 10 mm in size and to get anything approaching high definition, it must contain something like 1000×1000 pixels. A simple sum tells us that each of the one million pixels can be no larger than 10 microns! Modern microelectronics fabrication methods can easily make structures 100 times smaller than this but mixing different LED materials is a huge practical challenge. Enter the Porotech solution.

640nm red light emission from nano-porous InGaN (inset shows powered array of red LEDs) (courtesy Poro Technologies Limited)

Porotech was spun out of the University of Cambridge to exploit so-called nano-porous gallium nitride materials. InGaN (indium gallium nitride) is a compound semiconductor whose optoelectronic properties can be tuned not only by changing the precise composition but also by creating nano-scale voids.

The traditional way to produce red light from InGaN was to add aluminium and phosphorous atoms to produce red-emitting AlInGaNP. However making very small volumes of uniform semiconductor material from many elemental components is problematic as well as expensive. CEO and co-founder of Porotech Tongtong Zhu put it like this:

Porotech’s new class of porous GaN semiconductor material is now redefining what is possible – enabling the creation of efficient and bright native-red InGaN micro-LEDs and micro-displays

Tongtong Zhu CEO & co-founder, Porotech

Just how likely is this to happen? Over the summer Porotech have been busy adding three valuable components to the technology. In June a further £3M funding round was secured, led by Speedinvest. In August a key partnership was announced with major Chinese device manufacturer Jade Bird Display. Finally in September Porotech secured the services of former ARM executive Helen Adams as Chief Commercial Officer.

One mobile phone network provider used to claim that “the future’s bright, the future’s Orange”. Today for Porotech it seems “the future is bright, the future is red, green, blue, in fact any colour you want!”

Find out more about Porotech’s technology here.

Discover more about the Jade Bird Display venture here.

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