Solar ♦ news digest
by Kapadia et al in Scientific Reports,3, Article number 2275. doi:10.1038/srep02275 The full paper can be accessed via the link
http://www.nature.com/srep/2013/130724/srep02275/full/ srep02275.html The U.S. Department of Energy helped fund this research.
IQE revenues balloon by 80 percent
UC Berkeley engineers could help make high-end solar cells, currently used in satellites and other space and military applications, affordable for consumer markets. (iStockPhoto)
The conventional growth of III-Vs requires expensive epitaxial growth substrates, low precursor utilisation rates, long growth times, and large equipment investments. Addressing this issue, UC Berkeley researchers decided to explore cheaper ways to grow the III-V material indium phosphide (InP). They demonstrated that InP can be grown on thin sheets of metal foil in a process that is faster and cheaper than traditional methods, yet still comparable in optoelectronic characteristics. The researchers used a process they call Vapour Liquid Solid (VLS) growth. In this research, the scientists deposited indium films onto electropolished molybdenum foils by either electron- beam (e-beam) evaporation or electroplating, followed by e-beam evaporation of a 50 nm silicon oxide (SiOx) cap. The Mo/In/SiOx stack was then heated in hydrogen to a growth temperature above the melting point of indium (~157°C). After temperature stabilisation, phosphorous vapour was introduced into the chamber. The diffusion of phosphorous vapour through the capping layer and dissolution in the liquid indium resulted in the precipitation of solid InP crystals.
The development of products including gallium nitride materials and compound semiconductors on silicon projects are progressing well
IQE plc, a global supplier of advanced semiconductor wafer products and wafer services to the semiconductor industry, provides a trading update for the six months ended 30th June 2013.
The Board expects first-half performance to be ahead of market expectations, with first-half revenues approaching £63 million, EBITDA in excess of £10 million and net debt below £39 million. This represents revenue growth of over 80 percent, and EBITDA growth of over 150 percent compared with the first half of 2012. Sales growth was primarily driven by the wireless division, which included contributions from the RFMD and Kopin acquisitions.
The wireless market has continued to grow in line with expectations, driven by the increasing adoption of more sophisticated communication devices including 4G and LTE smartphones and tablets, and newly launched dual band wifi (802,11ac). These advanced products demand the highest levels of RF performance which can only be delivered by compound semiconductor enabled front end solutions.
The integration of the RFMD and Kopin acquisitions has been successfully completed as planned. IQE says work to realise the projected synergies is progressing well. The Board will provide a full update on this progress with the Group’s half year results.
Scanning electron micrograph of the InP (Credit: Ali Javey, Rehan Kapadia and Zhibin Yu)
Using this technique they demonstrated high quality 1 - 3 μm thick InP thin-films on molybdenum foils with ultra-large grain size up to 100 μm. The researcher says this is about 100 times larger than those obtained by conventional growth processes such as MOCVD. The films exhibited electron mobilities as high as 500 cm2/V-s and minority carrier lifetimes as long as 2.5 ns. What’s more, under 1-sun equivalent illumination, photoluminescence efficiency measurements indicated that an open circuit voltage of up to 930 mV can be achieved, only 40 mV lower than measured on a single crystal reference wafer. This work is described in detail in the paper, “A direct thin-film path towards low-cost large-area III-V photovoltaics,”
The photonics business is also making good progress with several applications in transition from research and development into production. Notably, these include a number of advanced laser (VCSEL) products for consumer, industrial and medical applications such as: optical communications devices for short range optical links; data centres and broadband delivery; optical devices for gesture recognition; gaming and cosmetic applications; and lasers for projection, medical and defence applications.
Advanced CPV solar technology acquired through the investment in Solar Junction and the exclusive seven year license agreement, is now in the final stages of qualification. The Group remains on track for this business to achieve end customer qualification and move into volume production during H2 2013.
The development of advanced products including GaN materials and the Group’s compound semiconductors on silicon projects are progressing well. They are building a
August/September 2013
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