Contact

Dr. Jürgen Lindner
Head
Magnetism
j.lindner hzdr.de
Phone: +49 351 260 - 3221

News

Conferences/workshops

Bachelor/master theses

FWIN calendar

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Prof. Dr. Manfred Helm

Direktor

 

Institut für Ionenstrahlphysik und Materialforschung
Helmholtz-Zentrum
Dresden-Rossendorf e.V.

Tel.: +49-351-260-2260 (Büro)
Tel.: +49-351-260-2345 (Sekretariat)
Fax: +49-351-260-3285
E-Mail: M.Helm@hzdr.de

Institut für Angewandte Physik (IAPP)
TU Dresden

George-Bähr-Straße 1
01069 Dresden

Tel.: + 49-351-463-33255
 

Prof. Dr. Manfred Helm - Porträt für Web-Visitenkarte


Research:

  • My research is focused on the electronic and optical properties of semiconductors and semiconductor nanostructures, mainly using ultrafast and THz spectroscopy. An important device for our research is the free-electron laser FELBE at HZDR.
  • Other interests: THz emitters and detectors, intersubband transitions, silicon photonics, magnetic semiconductors.
  • Author or co-author of over  >300 publications, >4000 citations, Hirsch Index 34.
  • A full publication list (ordered chronologically or according to citations) can be found in my  ResearcherID. Some recent and important publications can be found below.

Teaching:

  • Every winter term: Vorlesung  Halbleiter-Quantenstrukturen, Di. 5.DS,  BEY 98 (third year Bachelor, or Master).
  • For other teaching activities, please check „Lehre“
  • Topics for Bachelor, Master, and PhD theses can be found here.

Brief CV

1978-1983 Physics studies at the University of Innsbruck, Austria
1983-1987 Ph.D. in Physics at the University of Innsbruck, Austria
1987 - 1990 Researcher at Bellcore in Red Bank, NJ, USA
1990 - 2000 Institut für Halbleiterphysik, University of Linz, Austria
1993 Habilitation
1997 Associate Professor
Since 2000 Director of the Institute of Ion Beam Physics and Materials Research (HZDR) and Full Professor at the Institute for Applied Physics at the TU Dresden

Other activities

Awards
  • Fritz Kohlrausch Award of the Austrian Physical Society (1992)
  • Erich Schmid Award for Solid State Physics of the Austrian Academy of Sciences (1995)
  • Kardinal-Innitzer-Förderungspreis für Naturwissenschaften (1996)
Visiting appointments & guest professorships
  • UCSB, Santa Barbara (1996), University of Tokyo (1999), Princeton University (2002), Université Paris VII (2005), Osaka University (2008)
Conference Chair
  • 5th International Conference on Intersubband Transitions in Quantum Wells” (ITQW '99), Bad Ischl, Austria, 7-11 Sept. 1999.
  • "International Workshop on Infrared Microscopy and Spectroscopy with Accelerator Based Sources" (WIRMS 2005), Rathen, Germany, 26 - 30 June 2005.
  • "International Conference on Superlattices, Nanostructures, and Nanodevices" (ICSNN 2012), Dresden, Germany, 22-27 July 2012.

Some recent publications:

2014:

M. Mittendorff, T. Winzer, E. Malic, A. Knorr, C. Berger, W. A. de Heer,  H. Schneider, M. Helm, S. Winnerl:
“Anisotropy of excitation and relaxation of photogenerated charge carriers in graphene”
Nano Lett. 14, 1504 (2014)

M. Khalid, E. Weschke, W. Skorupa, M. Helm, S. Q. Zhou:
“Ferromagnetism and impurity band in a new magnetic semiconductor: InMnP”
Phys. Rev. B 89, 121301(R) (2014)

J. Bhattacharyya, S. Zybell, F. Eßer, M. Helm, H. Schneider, L. Schneebeli, C. N. Böttge, B. Breddermann, M. Kira, S. W. Koch, A. M. Andrews, and G. Strasser:
„Magnetic control of Coulomb scattering and terahertz transitions among excitons”
Phys. Rev. B 89, 125313 (2014)

M. Teich, M. Wagner, D. Stehr, H. Schneider, M. Helm, C. N. Böttge, A. C. Klettke, S. Chatterjee,  M. Kira, S. W. Koch, G. Khitrova, H. M. Gibbs:
“Systematic investigation of terahertz--induced excitonic Rabi splitting”
Phys. Rev. B 89, 115311 (2014)

2013:

M. Teich, D. R. Stephan, S. Winnerl, H. Schneider, L. R. Wilson, M. Helm:
„Intersublevel dephasing in InAs/GaAs quantum dots below the Reststrahlen band”
Appl. Phys. Lett. 103, 252110 (2013)

Ming Xu, M. Mittendorff , R. J. B. Dietz, H. Künzel, B. Sartorius, T. Göbel, H. Schneider, M. Helm, S. Winnerl:
"THz generation and detection with InGaAs-based large-area photoconductive devices excited at 1.55 µm"
Appl. Phys. Lett. 103, 251114 (2013)

Xin Ou, A. Keller, M. Helm, J. Fassbender, S. Facsko:
“Reverse epitaxy of Ge: Ordered and facetted surface patterns”
Phys. Rev. Lett. 111, 016101 (2013)

M. Beck, I. Rousseau, M. Klammer, P. Leiderer, M. Mittendorff, S. Winnerl, M. Helm, G. N. Gol’tsman, J. Demsar:
“Transient increase of the energy gap of superconducting NbN thin films excited by resonant narrow-band terahertz pulses”
Phys. Rev. Lett. 110, 267003 (2013)

W. D. Rice, J. Kono, S. Zybell, S. Winnerl, J. Bhattacharyya, H. Schneider, M. Helm, B. Ewers, A. Chernikov, M. Koch, S. Chatterjee, G. Khitrova, H. M. Gibbs, L. Schneebeli, B. Breddermann, M. Kira, and S. W. Koch:
"Observation of forbidden exciton transitions mediated by Coulomb interactions in photoexcited semiconductor quantum wells"
Phys. Rev. Lett. 110, 137404 (2013)

M. Teich, M. Wagner, H. Schneider, M. Helm:
"Semiconductor quantum well excitons in strong, narrowband terahertz fields”
New J. Phys. 15, 065007 (2013)

M. Mittendorff, S. Winnerl, J. Kamann, J. Eroms, D. Weiss, H. Schneider, M. Helm:
“Ultrafast graphene-based broadband THz detector”
Appl. Phys. Lett.  103, 021113 (2013)

2012:

T. Winzer, A. Knorr, M. Mittendorff, S. Winnerl, M.-B. Lien, Dong Sun, T. B. Norris, M. Helm, E. Malic:
“Absorption saturation in optically excited graphene”
Appl. Phys. Lett. 101, 221115 (2012)

S. Prucnal, S.Q. Zhou, Xin Ou, H. Reuther, M. O. Liedke, A. Mücklich, M. Helm, J. Zuk, M. Turek, K. Pyszniak, W. Skorupa:
“InP nanocrystals on silicon for optoelectronic applications”
Nanotechnology 23, 485204 (2012)

S. Winnerl, R. Hubrich, M. Mittendorff, H. Schneider, M. Helm:
“Universal phase relation between longitudinal and transverse fields observed in focused terahertz beams”
New J. Phys. 14, 103049 (2012)

R. Jacob, S. Winnerl, M. Fehrenbacher, J. Bhattacharyya, H. Schneider, M.-T. Wenzel, H.-G von Ribbeck, L. M. Eng, P. Atkinson, O. G. Schmidt,  M. Helm:
"Intersublevel spectroscopy on single InAs-quantum dots by terahertz near-field microscopy"
Nano Lett. 12, 4336 (2012)

 

2011:

S. Winnerl, M. Orlita, P. Plochocka, P. Kossacki, M. Potemski, T. Winzer, E. Malic, A. Knorr, M. Sprinkle, C. Berger, W. A. de Heer, H. Schneider, M. Helm:

"Carrier relaxation in epitaxial graphene photoexcited near the Dirac point"

Phys. Rev. Lett. 107, 237401 (2011)

 

S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S.-Y. Yang, C.-H. Yang, M. T. Wenzel, R. Jacob, H.-G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng, and R. Ramesh:

“Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling”

Nature Communications 2, 249 (2011)

 

J. Krause, M. Wagner, S. Winnerl, M. Helm, D. Stehr:

“Tunable narrowband THz pulse generation in scalable large area photoconductive antennas”

Optics Express 19, 19114 (2011)

 

M. Wagner, M. Helm, M. S. Sherwin, D. Stehr:

“Coherent control of a THz intersubband polarization in a voltage controlled single quantum well”

Appl. Phys. Lett. 99, 131109 (2011)

 

S. Zybell, H. Schneider, S. Winnerl, M. Wagner, K. Köhler, M. Helm:

"Photoluminescence dynamics in GaAs/AlGaAs quantum wells under pulsed intersubband excitation"

Appl. Phys. Lett. 99, 041103 (2011)

 

S. Prucnal, S. Facsko, C. Baumgart, H. Schmidt, M. O. Liedke, L. Rebohle, A. Shalimov, H. Reuther, A. Kanjilal, A. Mücklich, M. Helm, J. Zuk, W. Skorupa:

"n-InAs nanopyramids fully integrated into silicon"

Nano Lett. 11, 2814 (2011)

 

O. Drachenko, A. Patanè, N.V. Kozlova, Q.D. Zhuang, A. Krier, L. Eaves, M. Helm:

“Cyclotron resonance mass and Fermi energy pinning in the In(AsN) alloy”

Appl. Phys. Lett. 98, 162109 (2011)

 

2010:

M. Wagner, H. Schneider, D. Stehr, S. Winnerl, A. M. Andrews, S. Schartner, G. Strasser, M. Helm:

„Observation of the intra-exciton Autler-Townes effect in GaAs/AlGaAs semiconductor quantum wells”

Phys. Rev. Lett. 105, 167401 (2010)

 

R. Jacob, S. Winnerl, H. Schneider, M. Helm, M. T. Wenzel, H.-G von Ribbeck, L. M. Eng, S. C. Kehr:

“Quantitative determination of the charge carrier concentration of sub-surface implanted silicon by IR-near-field spectroscopy”

Optics Express 18, 26206 (2010)

 

S. Q. Zhou, D. Bürger, W. Skorupa, P. Oesterlin, M. Helm, H. Schmidt:

“The importance of hole concentration in establishing carrier-mediated ferromagnetism in Mn doped Ge”

Appl. Phys. Lett. 96, 202105 (2010)

 

J. Potfajova , B. Schmidt, M. Helm, T. Gemming, M. Benyoucef, A. Rastelli, O. G. Schmidt:

“Microcavity enhanced silicon light emitting pn-diode”

Appl. Phys. Lett. 96, 151113 (2010)

 

2009:

E. A. Zibik, T. Grange, B. A. Carpenter, N. E. Porter, R. Ferreira, G. Bastard, D. Stehr, S. Winnerl, M. Helm, H. Y. Liu, M. S. Skolnick, L. R. Wilson:

Long lifetimes of quantum dot intersublevel transitions in the terahertz range”

Nature Materials 8, 803 (2009)

 

T. Herrmannsdörfer, V. Heera, O. Ignatchik, M. Uhlarz, A. Mücklich, M. Posselt, H. Reuther, B. Schmidt, K.-H. Heinig, W. Skorupa, M. Voelskow, C. Wündisch, R. Skrotzki, M. Helm, J. Wosnitza:

“Superconducting state in a gallium-doped germanium layer at low temperature”

Phys. Rev. Lett. 102, 217003 (2009)

 

D. Golde, M. Wagner, D. Stehr, H. Schneider, M. Helm, A.M. Andrews, T. Roch, G. Strasser, M. Kira, S.W. Koch:

“Fano signatures in the intersubband terahertz response of optically excited semiconductor quantum wells”

Phys. Rev. Lett. 102, 127403 (2009)

 

2000-2008:

S.C. Kehr, M. Cebula, O. Mieth, T. Härtling, J. Seidel, S. Grafström, L.M. Eng, S. Winnerl, D. Stehr, M. Helm:

“Anisotropy contrast in phonon-enhanced apertureless near-field microscopy using a free-electron laser”

Phys. Rev. Lett. 100, 256403 (2008).

 

S. Prucnal, J. M. Sun, W. Skorupa, M. Helm:

"Switchable two-color electroluminescence based on a Si metal-oxide-semiconductor structure doped with Eu"

Appl. Phys. Lett. 90, 181121 (2007)

 

S. Q. Zhou.; K. Potzger, G. Zhang, A. Mücklich, F. Eichhorn, N. Schell, R. Grötzschel, B. Schmidt, W. Skorupa, M. Helm, J. Fassbender:

“Structural and magnetic properties of Mn-implanted Si”

Phys. Rev B 75, 085203 (2007)

 

D. Stehr, M. Helm, C. Metzner, M. C. Wanke:

„Microscopic theory of impurity states in coupled quantum wells and superlattices”

Phys. Rev. B 74, 085311 (2006)

 

D. Stehr, C. Metzner, M. Helm, T. Roch, G. Strasser:

„Resonant impurity bands in semiconductor superlattices”

Phys. Rev. Lett. 95, 257401 (2005)

 

A. Dreyhaupt, S. Winnerl, T. Dekorsy, M. Helm:

„High-intensity THz radiation from a microstructured large area photoconductor"

Appl. Phys. Lett. 86, 121114 (2005)

 

M. P. Semtsiv, M. Ziegler, S. Dressler, W. T. Masselink, N. Georgiev, T. Dekorsy, M. Helm:

„Above room temperature operation of short wavelength (l=3.8 mm) strain-compensated In0.73Ga0.27As/AlAs quantum cascade laser”

Appl. Phys. Lett. 85, 1478 (2004).

 

J. Sun, T. Dekorsy, W. Skorupa, B. Schmidt, M. Helm:

"Origin of anomalous temperature dependence and high efficiency of silicon light-emitting diodes"

Appl. Phys. Lett. 83, 3885 (2003)

 

T. Dekorsy, V. A. Yakovlev, W. Seidel, M. Helm, F. Keilmann:

“Infrared phonon-polariton resonance of the nonlinear susceptibility in GaAs”

Phys. Rev. Lett. 90, 055508 (2003)

 

O. V. Misochko, N. Georgiev, T. Dekorsy, M. Helm:

“Two crossovers in the pseudogap regime of YBa2Cu3O7-x superconductors observed by ultrafast spectroscopy”

Phys. Rev. Lett. 89, 067002 (2002)

 

M. Helm (editor):

"Long-Wavelength Infrared Emitters Based on Quantum Wells and Superlattices"

Gordon and Breach, 2000 (book)

 

M. Helm:

"The basic physics of intersubband transitions"

in "Semiconductors and Semimetals", Vol. 62 (Willardson and Weber, Series Editors) Academic Press, 2000, p. 1-99

(review article)

 

And here some even older papers:

from Linz:

M. Helm, W. Hilber, G. Strasser, R. DeMeester, F. M. Peeters, A. Wacker:

"Continuum Wannier-Stark ladders strongly interacting by Zener resonances in semiconductor superlattices",

Phys. Rev. Lett. 82, 3120 (1999)

 

B. N. Murdin, W. Heiss, C. J. G. M. Langerak, S.-C. Lee, I. Galbraith, G. Strasser, E. Gornik, M. Helm, C. R. Pidgeon:

"Direct observation of the LO phonon bottleneck in wide GaAs/AlGaAs quantum wells"

Phys. Rev. B 55, 5171 (1997)

 

P. Kruck, M. Helm, T. Fromherz, G. Bauer, J. F. Nützel, G. Abstreiter:

"Long-wavelength, normal-incidence p-type Si/SiGe quantum well infrared photodetector with background limited performance up to 85 K"

Appl. Phys. Lett. 69, 3372 (1996)

 

M. Helm:

"Infrared spectroscopy and transport of electrons in semiconductor superlattices"

Semicond. Sci. Technol.10, 557 (1995)(review article)

 

T. Fromherz, E. Koppensteiner, M. Helm, G. Bauer, J. F. Nützel, G. Abstreiter:

"Hole energy levels and intersubband absorption in modulation doped Si/SiGe multi-quantum wells"

Phys. Rev. B 50, 15073 (1994)

 

from Bellcore:

G. Brozak, M. Helm, F. DeRosa, C.H. Perry, M. Koza, R. Bhat, S.J. Allen:

"Thermal saturation of band transport in a superlattice ",

Phys. Rev. Lett. 64, 3163 (1990)

 

P. England, J.R. Hayes, E. Colas, M. Helm:

"Hot electron spectroscopy of Bloch electrons in high-order minibands in semiconductor superlattices",

Phys. Rev. Lett. 63, 1708 (1989)

 

M. Helm, P. England, E. Colas, F. DeRosa, S.J. Allen:

"Intersubband emission from semiconductor superlattices excited by sequential resonant tunneling",

Phys. Rev. Lett. 63, 74 (1989)

 

from Innsbruck:

K. Unterrainer, M. Helm, E. Gornik, E. E. Haller, J. Leotin:

"Mode structure of the p-germanium far infrared laser with and without external mirrors: Single line oscillation"

Appl. Phys. Lett. 52, 564 (1988)