NEWS REVIEW
In-Situ monitoring speeds up InP nanowire production
NANOWIRES, sometimes called nanorods, are becoming more and more attractive for next generation LED and solar cell applications.
One of the reasons is the fact that epitaxial III-V nanowire arrays combine 1-dimensional electronic states with additional degrees of freedom for strain relaxation and resonant electromagnetic interaction.
The most critical parameters for nanowires’ optical response are their length and diameter. Usually, time consuming and destructive ex- situ methods like scanning electron microscopy (SEM) are used for characterisation before further processing.
But now, LayTec and the Nanometre Structure Consortium at Lund University in Sweden have jointly developed a solution for real-time quantitative monitoring of III-V nanowire growth.
The team of Lars Samuelson used LayTec’s spectroscopic in- situ reflectometer EpiR to monitor nanowire epitaxy in an AIXTRON 200/4 reactor. The image below shows the LayTec software display at the end of the MOCVD run where InP shells were grown on InP core nanowires.
The data of previous ex-situ analysis by SEM and spectroscopic reflectance were used by Nicklas Anttu of Lund University to develop numerical algorithms for deduction of the average length and
diameters of the growing nanowire ensemble. This work is described in more detail in the paper, “Optical Far-Field Method with Subwavelength Accuracy for the Determination of Nanostructure Dimensions in Large-Area Samples,” by N. Anttu et al, in Nano Letters, 2013, 13 (6), pp 2662 - 2667. DOI: 10.1021/nl400811q
Together with these algorithms, the in- situ spectroscopic measurements by EpiR provide information on the evolution of nanowire length and diameter during growth.
EpiR enables effective process optimisation, speeds up development and paves the way to future process transfer for industrial nanowire growth. LayTec believes in-situ metrology will be a must in nanowire applications in the near future.
GaN microelectronics device market booming
WHILE MILITARY APPLICATIONS continue to drive the GaN device market, commercial applications have emerged that will help fuel rapid market growth. The recently released Strategy Analytics GaAs and Compound Semiconductor Technologies Service (GaAs) Forecast and Outlook, “GaN MIcroelectronics Market Update: 2012-2017”, concludes that the overall GaN microelectronics device market closed 2012 with revenues of slightly less than $100 million.
The report also forecasts that commercial RF and power management applications will begin shipping in volume during the
forecast period and this activity will push the overall market to slightly more than $334 million by 2017.
“The GaN device market has been “about to take off” for a number of years,” notes Eric Higham, Director of the Strategy Analytics GaAs and Compound Semiconductor Technologies Service (GaAs). He continues, “Based on our most recent research, it appears there are segments of the commercial market, like CATV and wireless infrastructure that are seeing higher volumes, but the broad commercial market is still not quite into the
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www.compoundsemiconductor.net July 2013
production phase. We do anticipate seeing more of these commercial segments contribute over the period and this will be the driver for strong revenue growth.”
Asif Anwar, Director in the Strategy Analytics Strategic Technologies Practice (STP) adds, “Despite the interest and growth in commercial applications for GaN, military applications will continue to account for more than half of the GaN device revenue in 2017. The performance benefits of using GaN devices in military applications are clear and this will keep driving GaN usage.”
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