Florian Furtmayr

 
Year: 2013

Research

Nanostructures based on Group III-Nitrides

Overview

The group III-nitrides (InN, GaN, AlN and their alloys) exhibit several outstanding material properties. Their direct band gap can be controlled from 0.7 eV (InN) to 3.4 eV (GaN) and to the deep UV spectral range of 6.2 eV (AlN), allowing the fabrication of heterostructures, such as quantum wells, for optoelectronic applications as for example light emitting diodes, laser diodes or quantum well infrared photo detectors.

Other properties like a high chemical and thermal stability facilitate the application as chemical sensors in gaseous or liquid environment.

Combination of these material properties with the benefit of size reduction into the nanoscale regime makes the III-nitrides an excellent material platform for future applications in nano-electronics, nanooptics or nanoscaled sensors. Quasi one-dimensional (1D) semiconductor crystals show quantum confinement effects and a higher surface to volume ratio which strongly improves the detection limit for sensors.

 

Growth and Characterization

GaN nanorods can be fabricated using predeposited metal droplets (the so-called VLS, vapour liquid solid growth technique) or by a catalyst free self-assembled growth. Our fabrication technique is plasma assisted molecular beam epitaxy (MBE).

 

Figure 1: Self assembled GaN nanorods on Si(111) substrates
(SEM image, view of a cleaved edge).
Left: Undoped GaN. The average rod height is 700 nm and the diameter 40 nm.
Right: Heavily Si doped GaN. Scale bars are 500nm.

 

The formation of III-nitride nanorods with hexagonal wurtzite on Si(111) substrates is possible by carefully controlling the substrate temperature and the III-V ratio (i.e. the flux ratio between Ga and N). The dimensions can be adjusted via the growth parameters and growth time. Typical values are 30 nm to 80 nm in diameter and 500 to 2500 nm in length.

 Figure 2: By varying the V-III ratio from intermediate conditions (left) towards more and more nitrogen rich conditions (center: V-III ratio changed by factor 2; right: by factor 3.2) one can change from an almost coalesced layer to isolated nanorods. Scale bars are 500 nm.

 

Another advantage of nanorods compared to a continuous film is the significantly reduced defect density. The single nanorods itself are almost defect free of dislocations, which offers not only the possibility to investigate basic material parameters in a higher precision than in nitride films but also allows to improve the performance of optoelectronic devices.

Currently my work is focused on the growth of Si- and Mg-doped GaN nanorods over a wide range of dopant concentrations and on the investigation of the influence of doping on the growth kinetics and optical properties.

 

Funding

This work is part of the NAWACS (Nano Wire Arrays for Multifunctional Chemical Sensors) project which is supported by the DFG (Ei 518/2-1) within the transnational call NanoSci-ERA. Further work on nanodiks embedded in AlGaN/GaN nanowires is carried out within the DOTSENSE project, funded by the 7th framework programme of the European Commission.

 

Publications

Self-assembled GaN nanowires on diamond

Nano Letters 12, 2199 (2012)

F. Schuster | F. Furtmayr | R. Zamani | C. Magen | J. R. Morante | J. Arbiol | J. A. Garrido | M. Stutzmann

Online Reference

Optical characterization of AlGaN/GaN quantum disc structures in single nanowires

physica status solidi (c), 7, 2233-2235 (2010)

L. Rigutti | F. Fortuna | M. Tchernycheva | A. D. L. Bugallo | G. Jacopin | F. H. Julien | F. Furtmayr | M. Stutzmann | M. Eickhoff

Online Reference

Origin of energy dispersion in Al_xGa_(1-x)/GaN nanowire quantum discs with low Al content

Phys. Rev. B 82, 235308 (2010)

L. Rigutti | J. Teubert | G. Jacopin | F. Fortuna | M. Tchernycheva | A. D. L. Bugallo | F. H. Julien | F. Furtmayr | M. Stutzmann | M. Eickhoff

Online Reference

Photoluminescence polarization properties of single GaN nanowires containing AlxGa1-xN/GaN quantum discs

Phys. Rev. B 81 045411 (2010)

L. Rigutti | M. Tchernycheva | A. du Luna Bugallo | G. Jacopin | F. H. Julien | F. Furtmayr | M. Stutzmann | M. Eickhoff | R. Songmuang | F. Fortuna

Online Reference

Analysis of polarization-dependent photoreflectance studies for c-plane GaN films grown on a-plane sapphire

Phys. Status Solidi A 206, 773 (2009)

M. Röppischer | R. Goldhahn | C. Buchheim | F. Furtmayr | T. Wassner | M. Eickhoff | C. Cobet | N. Esser

Online Reference

Triple-twin domains in Mg doped GaN wurtzite nanowires: structural and electronic properties of this zinc-blende-like stacking

Nanotechnology 20 14574 (2009)

J. Arbiol | S. Estradé | J. D. Prades | A. Ciera | F. Furtmayr | C. Stark | A. Laufer | M. Stutzmann | M. Eickhoff | M. H. Gass | A. L. Bleloch | F. Peió | J. R. Morante

Online Reference

Nucleation and growth of GaN nanorods on Si (111) surfaces by plasma-assisted molecular beam epitaxy - The influence of Si- and Mg-doping

Journal of Applied Physics 104 034309 (2008)

F. Furtmayr | M. Vielemeyer | M. Stutzmann | S. Estradé | F. Peirò | J. R. Morante | M. Eickhoff

Online Reference

Optical properties of Si- and Mg-doped gallium nitride nanowires grown by plasma-assisted molecular beam epitaxy

Journal of Applied Physics 104 074309 (2008)

F. Furtmayr | M. Vielemeyer | M. Stutzmann | A. Laufer | B. K. Meyer | M. Eickhoff

Online Reference

Stark shift of interband transitions in AlN/GaN superlattices

Applied Physics Letters 90 241906 (2007)

C. Buchheim | R. Goldhahn | A. T. Winzer | G. Gobsch | U. Rossow | D. Fuhrmann | A. Hangleiter | F. Furtmayr | M. Eickhoff

Online Reference

Impact of silicon incorporation on the formation of structural defects in AlN

JOURNAL OF APPLIED PHYSICS 100 113531 (2006)

M. Hermann | F. Furtmayr | F. M. Morales | O. Ambacher | M. Stutzmann | M. Eickhoff

Online Reference

Highly Si-doped AlN grown by plasma-assisted molecular-beam epitaxy

APPLIED PHYSICS LETTERS 86 19 192108 (2005)

M. Hermann | F. Furtmayr | A. Bergmaier | G. Dollinger | M. Stutzmann | M. Eickhoff

Online Reference

TUM Technische Universität München TUM Technische Universität München Physik Department Elektrotechnik und Informationstechnik TUM Technische Universität München
 

Events & News

17 Jan 2018

ERC Consolidator Grant for Gregor Koblmüller   more

10 Aug 2017

Best Poster Awards for Ganpath Veerabathran and Alexander Andrejew at iNOW 2017   more

27 Jun 2017

Best Poster Award at Nanowire Week for Jochen Bissinger   more

15 Mar 2017

Dr. Kai Müller admitted to the “Junges Kolleg” of the Bavarian Academy of Sciences   more

27 Feb 2017

Two-photon pulses from a single two-level system   more

Seminars

January 26, 2018

Reliability of hexagonal boron nitride dielectric stacks for CMOS applications   more

January 23, 2018

Helical states, spin-orbit coupling, and phase-coherent transport in InAs nanowires   more

January 16, 2018

New insights into novel (and conventional) materials using polarization-sensitive infrared magneto-spectroscopy   more