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Outlook 2014: The growing importance of optoelectronics

From ultra-efficient LEDs to coupling for isolation, optoelectronic semiconductors are increasingly important in applications ranging from lighting and factory automation to renewable energy and smart metering.

The semiconductor industry has endured a challenging time since the global financial meltdown of 2008, although IDC predicted in its 2012 forecast that the $295billion sector would return to growth of 3 to 4% in 2013.

Optoelectronics represents some 6% of the market, but is the fastest growing segment according to analyst Transparency Market Research.
Analysts tend to agree that LEDs will drive most of the growth in this sector for the immediate future – not least in terms of high brightness LEDs (HB-LEDs) as solid state lighting continues to replace traditional alternatives.

It was always predicted that LEDs would overtake Compact Fluorescent Lamps (CFL) in both commercial and residential interior lighting applications. LEDs are also making inroads in street lighting, as pilot schemes that proved significant cost savings were achievable without compromising safety give way to larger scale rollouts.

The EU Lighting Directive is a major piece of legislation imposing tough restrictions on lighting technologies and lamp power ratings. All clear incandescent and conventional halogen lamps with energy ratings less than C have been prohibited from sale since 2012. Almost all lamps will be required to have an energy rating of B or better by 2016. This progression favours the very low power consumption and high luminous efficacy of LEDs.

US legislation is more specific in backing LED technology. The Department of Energy's (DoE) Solid State Lighting Program calls for cooperation with the lighting and components industries to direct R&D, set goals and establish industry standards for product evaluation and reporting. A 2013 DoE annual report suggests solid state lighting could save some 217TWhr – around one third of the total energy consumed by lighting in the US today – by 2025. To reach this goal, the programme calls for further improvements in luminaire efficacy, to 200lumen/W, and wants to see solid state lighting provide 60% of the nation's total lumen-hours consumption.

LED vendors continue to drive technology forward at both chip and package level, improving aspects such as light extraction and thermal efficiency. Cost, of course, is an important factor governing pace of adoption. To this end, Toshiba announced a significant breakthrough at the end of 2012 that reduces the cost of producing high performing devices. Whereas white LEDs have been produced on expensive sapphire substrates in relatively small 2in or 4in wafers, the company's new gallium nitride on silicon (GaN on Si) substrate technology is a high performance alternative that allows use of more cost effective 8in wafers.

There is also an ongoing requirement for manufacturers to help the lighting industry design more effectively with LEDs. This demands extra field engineering strength, as well as reference material and tools that meet the special requirements of lighting designers who may have little or no experience of circuit level design. Given improving support, next generation lighting class LEDs (such as Toshiba's TL1Fx series with efficacy among the best in its class), and further technical innovation to cut cost and boost reliability, it is anticipated that the global white LED market will exceed $15bn by 2016.

Another notable growth area comes in the form of optocouplers (photocouplers). Increasingly strict safety legislation and evolving requirements in markets ranging from the industrial sector to smart meters and hybrid/electric vehicles (HEVs) support strong growth in this segment.

Demands to miniaturise equipment and support more functionality while meeting strict IEC regulations on creepage/clearance and isolation, for example, are driving innovation. At Toshiba, this includes developing couplers in packages such as the four pin SO6 which, despite measuring just 7 x 3.7 x 2.1mm, maintains minimum creepage and clearance distances of 5mm and has an internal isolation thickness of 0.4mm.

The result is an ultra miniature device with an isolation voltage of 3750V rms – satisfying the IEC 60747-5-5 and UL1577 standards and enabling engineers to meet tough equipment safety standards such as IEC 60950. Extended temperature operation (typically from -40 to 125°C) helps address the demands of harsh industrial or outdoor environments.

The IEC standards are applicable to a wide variety of industrial equipment and white goods, where typical coupler applications include IGBT gate drives, high speed data communications interfaces and galvanic isolation. At the same time, designers can replace traditional electromechanical relays with smaller, more rugged optocouplers that offer reduced maintenance and service requirements.

As well as electromechanical replacement, opportunities for optocouplers include 'green field' applications such as hybrid/electric vehicles, smart meters and solar energy. Again, reliability and small size give optocouplers an advantage over electromechanical devices; not to mention addressing requirements for high corrosion resistance that are particularly important for outdoor operation.

The opportunity in the hybrid vehicle market is appreciable. Toyota announced in April 2013 that it had sold more than 5m hybrid vehicles, including plug in hybrids, worldwide. The Prius, Toyota's most famous hybrid model, celebrates its 16th birthday in December 2013 and the company now has 19 hybrid models in its range. Total hybrid vehicle sales from all manufacturers now exceed 4.5m per annum and markets are sustaining double digit growth. Potentially, each vehicle will use multiple optocouplers, for driving multiphase Intelligent Power Modules (IPMs) and in the motor sensing circuitry, as well as in CAN bus infrastructures.

These, of course, are widely used in conventional vehicles as well as hybrids. Toshiba currently has devices capable of data rates up to 20Mbit/s for logic signal transmission and IPM drive applications.

The solar power industry has experienced declining growth recently due to the global recession and changing government subsidies. While growth is sure to return, the imperative to increase energy efficiency in key electrical subsystems such as the inverter is always present. Optoelectronic innovations helping to save power include low-voltage couplers capable of operating from supplies as low as 10V. This also allows a simpler power supply design, saving cost while boosting energy harvesting capability. Both of these gains move the solar industry towards its goal of price parity with conventional fossil fuel.

One green energy market that is certain to take off, thanks to widespread government backing, is smart meters. Governments from North America to Europe and Asia are committed to carbon reduction and clean energy programmes, and large scale adoption of smart meters has a significant role to play in helping reduce energy consumption and permit greater reliance on renewables.

The EU wants smart meter penetration to reach 80% by 2020. There are currently some 300 smart meter projects across Europe, representing an investment of around €6bn. Price, performance and power consumption are the key figures of merit for opto devices that provide energy-efficient communication and protection, which call for safe and economical packages such as the SO6 and current consumption close to 1mA.

It is clear that in 2014 and beyond, more engineers than ever will be tasked with designing optoelectronic semiconductors into their applications. Careful component selection and the availability of supplier support, tools and reference documentation will all be key factors in helping OEMs capitalise on the growing number of opportunities that the rapid evolution of optoelectronic technologies has to offer.

Toshiba Electronics Europe
Toshiba Electronics Europe (TEE) is the European electronic components business of Toshiba Corporation – a world leading diversified manufacturer, solutions provider and marketer of advanced electronic and electrical products and systems.

TEE offers one of the industry's broadest IC and discrete product lines including high end memory, microcontrollers, ASICs, ASSPs and display products for automotive, multimedia, industrial, telecoms and networking applications. The company also has a range of power semiconductor solutions and storage products.

Founded in 1875, Toshiba operates a global network of more than 590 consolidated companies, with 206,000 employees and annual sales surpassing $61billion. TEE, formed in 1973 to provide design, manufacturing, marketing and sales support, employs approximately 300 people in Europe.

Matthias Diephaus is senior manager of opto semiconductors for Toshiba Electronics Europe.

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Matthias Diephaus

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