FRAUNHOFER INSTITUT E FOR LASER TECHNOLOGY ILT
PRESS RELEASE
PRESS RELEASE
November 7, 2014 || Page 1 | 3
New industrial research technique for analyzing gallium nitride on the
nanometer scale
Gallium nitride is difficult to produce and difficult to handle – and the key to the development of
blue LEDs, which won this year’s Nobel Prize in Physics. The award went to three Japanese
researchers who were the first to produce high-quality gallium nitride (GaN) layers and put them
into series production back in 1993. Now, researchers and engineers around the world are working
on analyzing and optimizing this material. The Fraunhofer Institute for Laser Technology ILT has
worked closely with RWTH Aachen University’s I. Institute of Physics (IA) to develop an analysis
technology that, for the very first time, allows the structural and electronic properties of GaN and
GaN composites to be studied optically on the nanometer level.
Industry’s need for mass-producible LEDs is growing, whether for smartphone, computer
and TV screens or for the lighting sector. One important reason is that LEDs use many
times less energy than incandescent bulbs, halogen bulbs or even energy-saving bulbs. The
development of the blue LED was the last step in creating white LED light – a particularly
pleasant light that significantly boosts user acceptance of the technology, for instance in
home applications. Developing increasingly efficient components will rely on a quick and
cost-effective analysis technique.
Optical analysis on the nanometer scale
The resolution of conventional optical microscopes reaches its physical limits when
confronted with objects on the nanometer scale. Because of the light source employed,
tiny structures in the nanometer range – such as those you find in modern semiconductor
components – cannot be brought into focus. This rules out optical analysis techniques.
Near-field microscopy circumvents this fundamental limitation and penetrates the
nanometer domain to provide an optical view. This places extremely high demands on the
light source used.
Aachen laser system for using near-field microscopy techniques on gallium nitride
In collaboration with fellow researchers from the Chair for Experimental Physics at RWTH
Aachen University, scientists from Fraunhofer ILT have spent the past few years
developing an innovative, broadband tunable laser system that is geared toward the
particular requirements of semiconductor analysis. Wavelength can be adjusted to the
material under inspection, which enables the new system to investigate a wide range of
Editorial Notes
Dipl.-Phys. Axel Bauer | Head of Marketing and Communications | Phone +49 241 8906-194 | axel.bauer@ilt.fraunhofer.de
Petra Nolis M.A. | Leader Communications Group | Phone +49 241 8906-662 | petra.nolis@ilt.fraunhofer.de
Fraunhofer Institute for Laser Technology ILT | Steinbachstraße 15 | 52074 Aachen, Germany | www.ilt.fraunhofer.de
Steinbachstraße 15 | 52074 Aachen, Germany | www.ilt.fraunhofer.de
FRAUNHOFER INSTITUT E FOR LASER TECHNOLOGY ILT
materials. In contrast to the solutions available on the market to date and those employed
in research and development, the new system from Aachen provides the means for much
faster spectroscopic analyses. It has also opened up access to material systems that were
beyond the capacities of previous systems. This includes GaN and GaN composites.
Using the new analysis system, last year the researchers in Aachen were able to obtain an
optical 2D image showing tensions in the crystal structure of undoped GaN wafers for the
very first time. Computer simulations helped quantify the exact extent of the tension.
Recently the technique was also applied to a variety of doped GaN layers within complex
structures. It’s the first time an optical technique has been available to study the structural
and electronic properties of GaN and GaN composites on the nanometer scale.
Cost-effective, precise and non-destructive
Near-field microscopy offers cost and quality benefits over standard analysis techniques.
The structural properties of thin GaN layers are currently studied using transmission
electron microscopy; however, the costs incurred are extremely high, due in part to the
laborious sample preparation process. Near-field analysis can usually be conducted
without any preparation. Another benefit concerns secondary ion mass spectrometry,
which is used to study the electronic properties. Although this technique can be used to
determine electronic properties along an axis at the nanometer level, it isn’t yet possible to
laterally ascertain the concentration of doping atoms at a comparable resolution. The
technique also damages the samples. In contrast, near-field microscopy offers nanometerscale resolution in all dimensions. It is a completely non-destructive technique and can be
implemented under normal conditions.
Potential applications for the analysis system
Near-field microscopy is suitable for a range of applications. When used in close
consultation with the developers of new semiconductor components, for instance, the
method can help optimize process parameters in a targeted way. The analysis also aids in
the understanding of physical processes from a very early stage in development,
particularly at the interfaces between the individual layers. These findings can shape
subsequent development stages significantly. In high-frequency and power electronics,
too, GaN is becoming more and more common as a component due to its physical
properties. Near-field microscopic analysis techniques are ideally suited for researching
these materials.
PRESS RELEASE
November 7, 2014 || Page 2 | 3
FRAUNHOFER INSTITUT E FOR LASER TECHNOLOGY ILT
Picture:
Near-field microscope with a
fragment of a gallium nitride wafer.
Picture Source: Fraunhofer ILT,
Aachen, Germany.
PRESS RELEASE
November 7, 2014 || Page 3 | 3
The Fraunhofer-Gesellschaft is the largest organization for applied research in Europe. Its research activities are conducted by 67 Fraunhofer Institutes at
numerous locations throughout Germany. The Fraunhofer-Gesellschaft employs a staff of more than 23,000, who work with an annual research budget
totaling 2 billion euros. Of this sum, 1.7 billion euros is generated through contract research. More than 70 percent of the Fraunhofer-Gesellschaft’s
contract research revenue is derived from contracts with industry and from publicly financed research projects. Affiliated research centers and
representative offices around the world provide contact with regions of greatest importance to present and future scientific progress and economic
development.
For further information
Dr. Fabian Gaußmann | Laser Measurement Technology | Phone +49 241 8906-489 | fabian.gaussmann@ilt.fraunhofer.de
Fraunhofer Institute for Laser Technology ILT, Aachen, Germany | www.ilt.fraunhofer.de
Prof. Thomas Taubner | Institute of Physics (IA) | Phone +49 241 80 20260 | taubner@physik.rwth-aachen.de
RWTH Aachen University | www.rwth-aachen.de
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