III-V Nanowires for Optoelectronics


The best-known bottom-up method resulting in uniaxial growth of nanowires utilizes the vapor-liquid-solid mechanism in which the formation of a solid nanowire from the vapor phase is mediated by a tiny liquid metal droplet. We employ this approach (using Ga as the metal) for the synthesis of group-III-arsenide nanowires on Si(111) substrates. Selective area vapor-liquid-solid growth is readily obtained by patterning these substrates by electron beam lithography and reactive ion etching, leading to ordered nanowire arrays.   

An alternative bottom-up approach exists for materials that exhibit the tendency to form nanowires under suitable growth conditions spontaneously, i.e., without any external guidance. GaN is one of these materials, and is prone to the spontaneous formation of nanowires on a wide variety of substrates, including amorphous and crystalline insulators, semiconductors, and metals. We are currently focusing on the growth of group-III nitride nanowires on metallic substrates, and in particular on TiN – both as sputtered film and flexible foil – and graphene. In either case, ensembles of vertical GaN nanowires with excellent structural and optical properties can be obtained.


Spontaneously formed GaN nanowires invariably grow along the [000-1] direction, i.e., they are N polar. In order to synthesize Ga-polar group-III-nitride nanowires, we utilize a top-down process. In particular, we fabricate ordered arrays of nanowires from high-quality group-III-nitride layers and heterostructures by selective area sublimation. This complementary approach allows us to study phenomena depending on, for example, nanowire diameter in a systematic fashion.


These three different synthesis methods represent our platform for both fundamental investigations aimed at elucidating formation mechanisms and the fabrication of nanowire samples for dedicated studies of material properties and applications.

Selected Publications

7 Author H. Küpers , R. B. Lewis , A. Tahraoui , M. Matalla , O. Krüger , F. Bastiman , H. Riechert , L. Geelhaar

The diameter evolution of selective area grown Ga-assisted GaAs nanowires in molecular beam epitaxy

Source Nano Res. , 11 , 2885 ( 2018 )
DOI : 10.1007/s12274-018-1984-1 | 2956 Cite : Bibtex RIS
H. Küpers, R. B. Lewis, A. Tahraoui, M. Matalla, O. Krüger, F. Bastiman, H. Riechert, and L. Geelhaar

6 Author R. B. Lewis , P. Corfdir , J. Herranz , H. Küpers , U. Jahn , O. Brandt , L. Geelhaar

Self-assembly of InAs nanostructures on the sidewalls of GaAs nanowires directed by a Bi surfactant

Source Nano Lett. , 17 , 4255 ( 2017 )
DOI : 10.1021/acs.nanolett.7b01185 | Download arXiv: 1704.08014 | 2910 Cite : Bibtex RIS
R. B. Lewis, P. Corfdir, J. Herranz, H. Küpers, U. Jahn, O. Brandt, and L. Geelhaar

5 Author S. Fernández-Garrido , M. Ramsteiner , G. Gao , L. A. Galves , Bharat Sharma , P. Corfdir , G. Calabrese , Z. de Souza Schiaber , C. Pfüller , A. Trampert , J. M. J. Lopes , O. Brandt , L. Geelhaar

Molecular Beam Epitaxy of GaN Nanowires on Epitaxial Graphene

Source Nano Lett. , 17 , 5213 ( 2017 )
DOI : 10.1021/acs.nanolett.7b01196 | 2906 Cite : Bibtex RIS
S. Fernández-Garrido, M. Ramsteiner, G. Gao, L. A. Galves, Bharat Sharma, P. Corfdir, G. Calabrese, Z. de Souza Schiaber, C. Pfüller, A. Trampert, J. M. J. Lopes, O. Brandt, and L. Geelhaar

4 Author R. B. Lewis , L. Nicolai , H. Küpers , M. Ramsteiner , A. Trampert , L. Geelhaar

Anomalous strain relaxation in core-shell nanowires via simultaneous coherent and incoherent growth

Source Nano Lett. , 17 , 136 ( 2017 )
DOI : 10.1021/acs.nanolett.6b03681 | 2824 Cite : Bibtex RIS
R. B. Lewis, L. Nicolai, H. Küpers, M. Ramsteiner, A. Trampert, and L. Geelhaar

3 Author V. M. Kaganer , S. Fernández-Garrido , P. Dogan , K. Sabelfeld , O. Brandt

Nucleation, growth and bundling of GaN nanowires in molecular beam epitaxy: Disentangling the origin of nanowire coalescence

Source Nano Lett. , 16 , 3717 ( 2016 )
DOI : 10.1021/acs.nanolett.6b01044 | 2799 Cite : Bibtex RIS
V. M. Kaganer, S. Fernández-Garrido, P. Dogan, K. Sabelfeld, and O. Brandt

2 Author G. Calabrese , P. Corfdir , G. Gao , C. Pfüller , A. Trampert , O. Brandt , L. Geelhaar , S. Fernández-Garrido

Molecular beam epitaxy of single crystalline GaN nanowires on a flexible Ti foil

Source Appl. Phys. Lett. , 108 , 202101 ( 2016 )
DOI : 10.1063/1.4950707 | Download: PDF | 2794 Cite : Bibtex RIS
G. Calabrese, P. Corfdir, G. Gao, C. Pfüller, A. Trampert, O. Brandt, L. Geelhaar, and S. Fernández-Garrido

1 Author S. Fernández-Garrido , J. K. Zettler , L. Geelhaar , O. Brandt

Monitoring the formation of nanowires by line-of-sight quadrupole mass spectrometry: a comprehensive description of the temporal evolution of GaN nanowire ensembles

Source Nano Lett. , 15 , 1930 ( 2015 )
DOI : 10.1021/nl504778s | 2684 Cite : Bibtex RIS
S. Fernández-Garrido, J. K. Zettler, L. Geelhaar, and O. Brandt


Dr. Lutz Geelhaar

Head of Department

+49 30 20377-359


Dr. Oliver Brandt

Senior Scientist

+49 30 20377-332

lab: -444