Main results of our work are and will be published in scientific journals. Here is an actual list of papers published by the consortium.
- X. Wang, U. Jahn, M. Mandl, T. Schimpke, J. Hartmann, J. Ledig, M. Straßburg, H.-H. Wehmann, A. Waag: Growth and characterization of mixed polar GaN columns and core-shell LEDs; Phys. Status Solidi A 212 (2015) 727-731
- M.A. Deeb, J.D. Wei, J. Hartmann, H.-H. Wehmann, A. Waag: Surface photovoltage behavior of GaN columns; Phys. Status Solidi A 212 (2015) 732-735
- S. Albert, A. Bengoechea-Encabo, J. Zuniga-Perez, P. de Mierry, P. Val, M.A. Sanchez-Garcia, E. Calleja: Selective area growth of GaN nanostructures: A key to produce high quality (11-20) a-plane pseudo-substrates; Appl. Phys. Lett. 105 (2014) 091902
- X. Wang, J. Hartmann, M. Mandl, M.S. Mohajerani, H.-H. Wehmann, M. Strassburg, A. Waag: Growth kinetics and mass transport mechanisms of GaN columns by selective area metal organic vapor phase epitaxy; J. Appl. Phys. 115 (2014) 163104 (http://dx.doi.org/10.1063/1.4871782)
- E. Raj, Z. Lisik, P. Niedzielski, L. Ruta, M. Turczynski, X. Wang, A. Waag: Modelling of MOCVD Reactor: New 3D Approach; J. Phys.: Conf. Ser. 494 (2014) 012019
- Z. Lisik, M. Turczynski, L. Ruta, E. Raj: Verification of Thermo-Fluidic CVD Reactor Model; J. Phys.: Conf. Ser. 494 (2014) 012020
- S. Albert, A. Bengoechea-Encabo, M. Sabido-Siller, M. Müller, G. Schmidt, S. Metzner, P. Veit, F. Bertram, M.A. Sánchez-García, J. Christen, E. Calleja: Growth of InGaN/GaN core-shell structures on selectively etched GaN rods by molecular beam epitaxy; J. Crystal Growth 392 (2014) 5-10
- A. Bengoechea-Encabo, S. Albert, J. Zuñiga-Perez, P. de Mierry, A. Trampert, F. Barbagini, M.A. Sanchez-Garcia, E. Calleja: Selective area growth and characterization of GaN nanocolumns, with and without an InGaN insertion, on semi-polar (11-22) GaN templates; Appl. Phys. Lett. 103 (2013) 241905
- S. Albert, A. Bengoechea-Encabo, X. Kong, M.A. Sanchez-Garcia, E. Calleja, A. Trampert: Monolithic integration of InGaN segments emitting in the blue, green, and red spectral range in single ordered nanocolumns; Appl. Phys. Lett. 102 (2013) 181103
- I.J. Griffiths, D. Cherns, X. Wang, A. Waag, H.-H. Wehmann: Characterisation of 3D-GaN/InGaN nanostructured light emitting diodes by transmission electron microscopy; J. Phys.: Conf. Ser. 471 (2013) 012018
- X. Wang, U. Jahn, J. Ledig, H.-H. Wehmann, M. Mandl, M. Straßburg, A. Waag: The MOVPE growth mechanism of catalyst-free self-organized GaN columns in H2 and N2 carrier gases; J. Cryst. Growth 384 (2013) 61-65
- S. Albert, A. Bengoechea-Encabo, M.A. Sánchez-García, X. Kong, A. Trampert, E. Calleja: Selective area growth of In(Ga)N/GaN nanocolumns by molecular beam epitaxy on GaN-buffered Si(111): from ultraviolet to infrared emission; Nanotechnology 24 (2013) 175303
- S. Albert, A. Bengoechea-Encabo, M.A. Sanchez-Garcia, E. Calleja, U. Jahn: Selective area growth and characterization of InGaN nanocolumns for phosphor-free white light emission; J. Appl. Phys. 113 (2013) 114306
- M. Mandl, X. Wang, T. Schimpke, C. Kölper, M. Binder, J. Ledig, A. Waag, X. Kong, A. Trampert, F. Bertram, J. Christen, F. Barbagini, E. Calleja, M. Strassburg: Group III nitride core-shell nano- and microrods for optoelectronic applications; Phys. Stat. Sol. RRL 7 (2013) 800-814
- X. Wang, S.F. Li, M.S. Mohajerani, J. Ledig, H.-H. Wehmann, M. Mandl, M. Strassburg, U. Steegmüller, U. Jahn, J. Lähnemann, H. Riechert, I. Griffiths, D. Cherns, A. Waag: Continuous-Flow MOVPE of Ga-Polar GaN Column Arrays and Core–Shell LED Structures; Crystal Growth and Design 13 (2013) 3475-3480
- X. Wang, S.F. Li, S. Fündling, H.-H. Wehmann, M. Strassburg, H.-J. Lugauer, U. Steegmüller, A. Waag: Mechanism of nucleation and growth of catalyst-free self-organized GaN columns by MOVPE; J. Phys. D: Appl. Phys. 46 (2013) 205101
Press Release - September 2014:
Innovation News: More productivity and luminous efficacy due to nano technology (in German)
Researchers of OSRAM were successful in producing a 3D nano LED for white light. By arranging many of these in an array the light emitting area can be larger than the respective wafer area. The prototype increases the area by a factor of 5 to 10. For the emission of white light a new fine grained phosphor was developed that fits in between the 3D LEDs.
Press Release - July 2012:
3-dimensional Light Emitting Diodes for future lighting technologies
The Institute of Semiconductor Technology at Technische Universität (TU) Braunschweig is engaged in an EU-research project 'GECCO' developing a new pioneering generation of white light emitting diodes. The innovative 3-dimensional assembly of the diodes is expected to provide more than tenfold the quantity of light output in comparison to those planar LEDs currently in use. The financial grant for this project amounts to a total sum of 3.8 million Euro, whereas the share of the TU Braunschweig amounts to 1.2 million Euro.
Already now, modern high-performance LEDs provide a bright light output at high efficiency and are meanwhile applied for automobile headlights, for example. At present, the production process for these kinds of LEDs is still not cost efficient enough and also the efficiency of these LEDs needs further improvement.
Tiny 'lighthouses' are more efficient
The international team of the GECCO project with their partners from Madrid, Bristol, Lodz, the OSRAM AG Munich and the OSRAM OS GmbH Regensburg is working hard on achieving their ambitious objectives.
Up to now, LEDs are being constructed in a planar way, meaning in layers and completely flat. The more light is being required, the more wafer area has to be produced, which is an expensive and laborious approach. The exceptional idea of the GECCO project is to assemble LEDs in a three-dimensional way so that actually every LED consists of a 'light emitting tower' from which the entire vertical surface is emitting light. Obviously the surface of the tower is much larger compared to the ground area of a planar LED. And in fact, it is exactly the gain of light emitting area that leads to a higher light output.
Thus, the manufacturing of an LED becomes much more cost-effective and as a result replacing ancient electric bulbs, halogen lamps as well as energy saving bulbs to LEDs is getting a lot more profitable. Considering the fact that currently 20 % of electrical energy worldwide is being utilized for illumination, this innovation provides an enormous potential as far as cost-effectiveness is concerned. In addition, LED lighting is particularly important for future electric mobility. Energy saving is of utmost importance in electric cars.
A million LEDs per square millimeter
The dimensions of the 'light emitting towers' are within the micrometer range. This means approximately one million LEDs fit on an area of one square millimeter. This process requires utmost precision which can only be achieved by applying nanotechnology manufacturing techniques.
The GECCO project is coordinated by Prof. Andreas Waag from the Institute of Semiconductor Technology, which is part of the Electrical Engineering Department of the Technische Universität Braunschweig.
Scanning electron microscopy image of 3D GaN pillars with an aspect ratio (height to width) of 10 as carcass of 3D LEDs.
With this project the Faculty of Electrical Engineering, Information Technology, Physics sets another example as to the further and ongoing strengthening of the UniversityÂ´s research profile in the specialization of NanoSystemsEngineering - this time in the true sense of the word - a bright and shining sign.
The Institute of Semiconductor (IHT) is an institution of Braunschweig University of Technology and belongs to the Faculty of Electrical Engineering, Information Technology, Physics. The institute and its 40 staff members are engaged in particular in the research of semiconductor nanostructures and their application among others for nanoLEDs, the hydrogene generation, gas sensors, thermoelectrical generators, high-temperature and nanoparticle-sensors as well as solar cells.
For further information, please contact:
Prof. Dr. Andreas Waag (Coordinator)
Institut für Halbleitertechnik der TU Braunschweig