Plessey Semiconductors

Lightening up in a semiconductor niche

High-volume manufacturing isn’t a strategy that makes sense for every company. Sometimes businesses in technology sectors feel they should step back from production to focus on development and support for customers.

This is the approach taken by Plessey Semiconductors, a company with a venerable name that is trying to establish its reputation as an innovator in the emerging industry of augmented reality. This new field combines digital and real-life images in a range of display applications for sectors including computer games or industrial design.

Plessey is based in Plymouth in south-west England, a long way from the glitziest centres of high-tech industry. But in a series of clean rooms near the office of Keith Strickland, co-chief executive, engineers and technicians are controlling sophisticated production processes that he says are ahead of his global rivals.

Strickland says the company’s potential is based on its expertise in a specialist area of light-emitting diodes called microLEDs. Mainstream LEDs - semiconductors that emit light - have revolutionised the global lighting industry in recent years by replacing older and less energy-efficient light sources.

“We lack the scale [for volume production],” Strickland says. “We have three [manufacturing] reactors that we use to create our microchips. Our biggest competitors [in LEDs generally] have hundreds.”

Big companies in the broad LED business include the US’s Cree, Osram of Germany, Philips of the Netherlands, Samsung in South Korea and Nichia of Japan.

Strickland adds: “We want to form partnerships with other companies in electronics that would do large scale manufacturing [based on our technology]. We will concentrate on development and making chips on a much smaller scale [for validating fabrication processes]”.

Plessey has followed the path of many other UK technology businesses by backing away from large-scale production and refocusing on product development supported by a limited amount of inhouse manufacturing.

Another trait that Plessey shares with others in UK manufacturing and technology is that its chosen product area is a niche within a bigger sector where competition is lower, and it has more scope to exploit its specialist skills. Plessey is competing in a narrow part of the LED business – which is itself a niche within the broader semiconductor field.

Plessey Semiconductors was started only in 2010 – but the Plessey name comes from a much older business. For more than 70 years the “old Plessey” was one of the UK’s mightiest engineering firms, making products from fuel pumps to telephone exchanges. The company was sold in 1988 and subsequently dismembered, leaving Strickland and the rest of his staff to build on the legacy of a Plessey subsidiary that had ventured into integrated circuits.

The driving force behind Plessey’s new incarnation was its founder, Michael LeGoff. The visionary Canadian engineer set out goals for turning the company into a sizeable LED manufacturer using special technology evolved from Cambridge University that he reckoned gave the company a competitive advantage. That approach was jettisoned in 2018 after Plessey’s financial backers argued that its rivals in the mainstream LED industry were too strong to overcome.

After the strategy switch, LeGoff left the company and Strickland – an electronics industry veteran and a long-time Plessey employee – took over the running of the company along with its chief financial officer, Iain Silvester.

The Plessey process is based on creating LED circuitry from ultra-thin layers of gallium nitride – an exotic material that can operate at higher frequencies and voltages than silicon.

The microLEDs that Plessey is focusing on are arrays of tiny semiconductors, each of them an LED typically measuring some 50 micrometres square.

A microLED array might measure 1.5cm-2cm in diameter and have 2 million LEDs embedded on it. Each can be driven independently, providing a tiny point of illumination – a pixel – on a display screen, making it possible to produce small but sharp and bright displays.

Having many emitters on a single chip gives microLEDs the potential to meet the requirements of new applications in virtual reality or augmented reality headsets, or in new versions of smart phones and watches.

In recent years Plessey has developed LEDs made from gallium nitride on a substrate of silicon, rather than the usual sapphire. Use of a silicon-based technology is highly useful in allowing microLEDs of this sort to go into large scale production.

“The electronics industry is used to silicon. This makes our technology much more attractive to the sorts of companies we want to partner with than processes based around other materials,” says Strickland.

Companies that are developing rival forms of microLEDs include Aledia of France and LuxVue in the US which is now part of Apple.

The clean rooms at Plessey’s HQ housing its production equipment will be used to try out new development ideas and for making small volumes of its microLEDs. It is impossible to imagine, says Strickland, that Plessey will go into volume production.

Looking ahead, Strickland says Plessey will aim to produce a “few hundred wafers” a month containing its microLEDs. Each wafer is 150mm in diameter.

Plessey has a partnership with Jasper Display, a Taiwanese semiconductor design company that is developing new sorts of chips for use in displays. It has a further co-operation agreement with Vuzix, a producer of “smart glasses” and other types of augmented reality equipment based in the US.

Plessey is also working with Nanoco, a US/UK maker of exotic “quantum dots” used in digital displays. The two businesses are each exploring how they could use some of the other’s ideas in their own developments.

Since the company was started in its current form by LeGoff it has received some £90m of investment from various sources. The majority owner is a venture capital company whose identity has not been disclosed.

“Over the next few years we will be looking for other strategic investors to come in which have an interest in the technology and markets that we are exploring,” says Strickland.

Revenues in 2018 came to roughly £20m – much of this “legacy” items such as photodiodes based on products made by Plessey in its pre-2010 incarnation. Of the total revenues, about a quarter came in from the specialist business of “grow-lights” LEDs for helping plant growth in “indoor farms” which are becoming increasingly popular in agriculture.