Prof. Dr. Manfred Helm



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

Tel.: +49-351-260-2260 (Büro)
Tel.: +49-351-260-2345 (Sekretariat)
Fax: +49-351-260-3285

Institut für Angewandte Physik (IAP)
TU Dresden
Nöthnitzer Str. 61

01069 Dresden

Tel.: + 49-351-463-33255

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


  • 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  >500 publications, >10,000 citations, Hirsch Index 51 (Google Scholar 61).
  • A full publication list (ordered chronologically or according to citations) can be found in my  ResearcherID. This is my Google Scholar account. Some recent and important publications can be found below.


  • Every winter term: Vorlesung  Semiconductor Quantum Structures, Di. 5.DS,  REC B214 (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

  • 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)
  • Fellow of the American Physical Society (APS) (2023)
Visiting appointments & guest professorships
  • UCSB, Santa Barbara (1996), University of Tokyo (1999), Princeton University (2002), Université Paris VII (2005), Osaka University (2008)
Conference Chair

Some recent publications:


Shuyu Wen, M. Saif Shaikh, O. Steuer, S. Prucnal, J. Grenzer, R. Hübner, M. Turek, K. Pyszniak, S. Reiter, I. Fischer, Y. Georgiev, M. Helm, Shaoteng Wu, Jun-Wei Luo, Shengqiang Zhou, Y. Berencén:
“Room-temperature extended short-wave infrared GeSn photodetector realized by ion beam techniques”
Appl. Phys Lett. 123, 081109 (2023)

Fangchao Long, M. Ghorbani-Asl, K. Mosina, Yi Li, Kaiman Lin, F. Ganss, R. Hübner, Z. Sofer, F. Dirnberger, A. Kamra, A. V. Krasheninnikov, S. Prucnal, M. Helm, Shengqiang Zhou:
"Ferromagnetic interlayer coupling in CrSBr crystals irradiated by ions"
Nano Lett. 23, 8468 (2023)

M. Helm, S. Winnerl, A. Pashkin, J. M. Klopf, J.-C. Deinert, S. Kovalev, P. Evtushenko, U. Lehnert, R. Xiang, A. Arnold, A. Wagner, S. M. Schmidt, U. Schramm, T. Cowan & P. Michel:
"The ELBE infrared and THz facility at Helmholtz-Zentrum Dresden-Rossendorf"
The European Physical Journal Plus 138, 158 (2023)

H. Arora, Z. Fekri, Y. N. Vekariya, P. Chava, K, Watanabe, T. Taniguchi, M. Helm, A. Erbe:
“Fully Encapsulated and Stable Black Phosphorus Field-Effect Transistors”
Advanced Materials Technologies 8, 2200546 (2023)


M. Hollenbach, N. Klingner, N.S. Jagtap, L. Bischoff, C. Fowley, U. Kentsch, G. Hlawacek, A. Erbe, N.V. Abrosimov, M. Helm, Y. Berencén, G.V. Astakhov:
“Wafer-scale nanofabrication of telecom single-photon emitters in silicon”
Nature Communications 13, 7683 (2022)

A. Echresh, S. Prucnal, Zichao Li, R. Hübner, F. Ganss, O. Steuer, F. Bärwolf, S. Jazavandi Ghamsari, M. Helm, Shengqiang Zhou, A. Erbe, L. Rebohle, Y. M. Georgiev:
„Fabrication of Highly n-Type-Doped Germanium Nanowires and Ohmic Contacts Using Ion Implantation and Flash Lamp Annealing”
ACS Appl. Electron. Mater. 4, 5256 (2022)

T. Venanzi, M. Selig, A. Pashkin, S. Winnerl, M. Katzer, H. Arora, A. Erbe, A. Patanè, Z. R. Kudrynskyi, Z. D. Kovalyuk, L. Baldassarre, A. Knorr, M. Helm, H. Schneider:
“Terahertz control of photoluminescence emission in few-layer InSe”
Appl. Phys. Lett. 120, 092104 (2022)

A. Seidl, R. Anvari, M. M. Dignam, P. Richter, Th. Seyller, H. Schneider, M. Helm, S. Winnerl:
„Pump-induced terahertz anisotropy in bilayer graphene“
Phys. Rev. B 105, 085404 (2022)

Juanmei Duan, P. Chava, M. Ghorbani-Asl, Y.F. Lu, D. Erb, L. Hu, A. Echresh, L. Rebohle, A. Erbe, A. V. Krasheninnikov, M. Helm, Yu-Jia Zeng, S.Q. Zhou, S. Prucnal:
“Self-Driven Broadband Photodetectors Based on MoSe2/FePS3 van der Waals n–p Type-II Heterostructures”
ACS Appl. Mater. Interfaces 14, 11927 (2022)

Mao Wang, Ye Yu, S. Prucnal, Y. Berencén, M. S. Shaikh, L. Rebohle, M. B. Khan, V. Zviagin, R. Hübner, A. Pashkin, A. Erbe, Y. M. Georgiev, M. Grundmann, M. Helm, R. Kirchner, S. Q. Zhou:
“Mid- and far-infrared localized surface plasmon resonances in chalcogen-hyperdoped silicon”
Nanoscale 14, 2826 (2022)


L. Balaghi, S. Shan, I. Fotev, F. Moebus, R. Rana, T. Venanzi, R. Hübner, T. Mikolajick, H. Schneider, M. Helm, A. Pashkin, E. Dimakis:
„High electron mobility in strained GaAs nanowires”
Nature Communications 12, 6642 (2021)

R. Rana, J. M. Klopf, C. Ciano, A. Singh, S. Winnerl, H. Schneider, M. Helm, A. Pashkin:
“Gold implanted germanium photoswitch for cavity dumping of a free-electron laser”
Appl. Phys. Lett. 118, 011107 (2021)

T. Venanzi, M. Selig, S. Winnerl, A. Pashkin, A. Knorr, M. Helm, H. Schneider:
“Terahertz induced energy transfer from hot carriers to trions in a MoSe2 monolayer”
ACS Photonics 8, 2931 (2021)

Juanmei Duan, P. Chava, M. Ghorbani-Asl, D. Erb, Liang Hu, A. V. Krasheninnikov, H. Schneider, L. Rebohle, A. Erbe1, M. Helm, Yu-Jia Zeng, Shengqiang Zhou, S. Prucnal:
“Enhanced trion emission in monolayer MoSe2 by constructing a type-I van der Waals heterojunction”
Advanced Functional Materials 31, 2104960 (2021)

S. Prucnal, A. Hashemi, M. Ghorbani-Asl, R. Hübner, Juanmei Duan, Yidan Wei, D. Sharma, D.R.T. Zahn, R. Ziegenrücker, U. Kentsch, A. V. Krasheninnikov, M. Helm, S.Q. Zhou:
“Chlorine doping of MoSe2 flakes by ion implantation”
Nanoscale 13, 5834 (2021)  

Zichao Li, Yufang Xie, Ye Yuan, Yanda Ji, V. Begeza, Lei Cao, R. Hübner, L. Rebohle, M. Helm, K. Nielsch, S. Prucnal, S.Q. Zhou:
“Phase Selection in Mn–Si Alloys by Fast Solid‐State Reaction with Enhanced Skyrmion Stability”
Advanced Functional Materials 31, 2009723 (2021)

K. Schultheiss, N. Sato, P. Matthies, L. Körber, K. Wagner, T. Hula, O. Gladii, J. E. Pearson, A. Hoffmann, M. Helm, J. Fassbender, H. Schultheiss:
“Time refraction of spin waves”
Physical Review Letters 126, 137201 (2021)


Mao Wang, E. García-Hemme, Y. Berencén, R. Hübner, Yufang Xie, L. Rebohle, Chi Xu, H. Schneider, M. Helm, S.Q. Zhou:
„Silicon-based Intermediate-band Infrared Photodetector realized by Te Hyperdoping”
Advanced Optical Materials 9, 2001546 (2020)

J. Schmidt, S. Winnerl, E. Dimakis, R. Hübner, H. Schneider, M. Helm:
“All-THz pump-probe spectroscopy of the intersubband AC-Stark effect in a wide GaAs quantum well”
Optics Express 28, 25358 (2020)

M. Hollenbach, Y. Berencén, U. Kentsch, M. Helm, G. Astakhov:
“Engineering telecom single-photon emitters in silicon for scalable quantum photonics”
Optics Express 28, 26111 (2020)

R. Rana, L. Balaghi, I. Fotev, H. Schneider, M. Helm, E. Dimakis, A. Pashkin:
“Nonlinear Charge Transport in InGaAs Nanowires at Terahertz Frequencies”
Nano Lett. 20, 3225 (2020)

T. Venanzi, H. Arora, S. Winnerl, A. Pashkin, P. Chava, A. Patanè, Z. D. Kovalyuk, Z. R. Kudrynskyi, K. Watanabe, T. Taniguchi, A. Erbe, M. Helm, H. Schneider:
“Photoluminescence dynamics in few-layer InSe”
Phys. Rev. Materials 4, 044001 (2020)

A. Singh, A. Pashkin, S. Winnerl, M. Welsch, C. Beckh, P. Sulzer, A. Leitenstorfer, M. Helm, H. Schneider:
Up to 70 THz bandwidth from an implanted Ge photoconductive antenna excited by a femtosecond Er:fibre laser
Light: Science & Applications 9, 30 (2020)


D. B. But, M. Mittendorff, C. Consejo, F. Teppe, N. N. Mikhailov, S. A. Dvoretskii, C. Faugeras, S. Winnerl, M. Helm, W. Knap, M. Potemski, M. Orlita:
“Suppressed Auger scattering and tunable light emission of Landau-quantized massless Kane electrons”
Nature Photonics 13,783 (2019)

L. Balaghi, G. Bussone, R. Grifone, R. Hübner, J. Grenzer, M. Ghorbani-Asl, A. V. Krasheninnikov, H. Schneider, M. Helm, E. Dimakis:
“Widely tunable GaAs band gap via strain engineering in core/shell nanowires with large lattice mismatch”
Nature Communications 10, 2793 (2019)

H. Arora, Y. Jung, T. Venanzi, K. Watanabe, T. Taniguchi, R. Hübner, H. Schneider, M. Helm, J. C. Hone, A. Erbe:
„Effective Hexagonal Boron Nitride Passivation of Few-Layered InSe and GaSe to Enhance Their Electronic and Optical Properties”
ACS Appl. Mater. Interfaces 11, 46 (2019)

Mao Wang, A. Debernardi, Y. Berencén, R. Heller, Chi Xu, Ye Yuan, Yufang Xie, R. Böttger, L. Rebohle, W. Skorupa, M. Helm, S. Prucnal, S.Q. Zhou:
“Breaking the doping limit in silicon by deep impurities”
Phys. Rev. Applied 11, 054039 (2019)


Ye Yuan, R. Hübner, M. Birowska, Chi Xu, Mao Wang, S. Prucnal, R. Jakiela, K. Potzger, R. Böttger, S. Facsko, J. A. Majewski, M. Helm, M. Sawicki, S.Q. Zhou, T. Dietl:
“Nematicity of correlated systems driven by anisotropic chemical phase separation”
Phys. Rev. Materials 2, 114601 (2018)

A. Singh, A. Pashkin, S. Winnerl, M. Helm, H. Schneider:
„Gapless broadband terahertz emission from a germanium photoconductive emitter”
ACS Photonics 5, 2718 (2018)

Mao Wang, Y. Berencén, E. García-Hemme, S. Prucnal, R. Hübner, Ye Yuan, Chi Xu, L. Rebohle, R. Böttger, R. Heller, H. Schneider, W. Skorupa, M. Helm, Shengqiang Zhou
“Extended infrared photoresponse in Te-hyperdoped Si at room-temperature”
Phys. Rev. Applied 10, 024054 (2018)

J. Braun, H. Schneider, M. Helm, R. Mirek, L.A. Boatner, R.E. Marvel, R.F. Haglund Jr., A. Pashkin: 
"Ultrafast Response of Photoexcited Carriers in VO2 at high pressure”
New Journal of Physics 20, 083003 (2018)


Ye Yuan, Chi Xu, R. Hübner, R. Jakiela, Roman Böttger, M. Helm, M. Sawicki, T. Dietl, S. Q.  Zhou:
“Interplay between localization and magnetism in (Ga,Mn)As and (In,Mn)As”
Phys. Rev. Materials 1, 054401 (2017)

B. Piętka, N. Bobrovska, D. Stephan, M. Teich, M. Król, S. Winnerl, A. Pashkin, R. Mirek, K. Lekenta, F. Morier-Genoud, H. Schneider, B. Deveaud, M. Helm, M. Matuszewski, J. Szczytko:
Doubly Dressed Bosons: Exciton Polaritons in a Strong Terahertz Field:
Phys. Rev. Lett. 119, 077403 (2017)

F. Wendler, M. Mittendorff, J. C. König-Otto, S. Brem, C. Berger, W. A. de Heer, R. Böttger, H. Schneider, M. Helm, S. Winnerl, E. Malic:
Symmetry-Breaking Supercollisions in Landau-Quantized Graphene
Phys. Rev. Lett. 119, 067405 (2017)

T. Winzer, M. Mittendorff, S. Winnerl, H. Mittenzwey, R. Jago, M. Helm, E. Malic, A. Knorr:
"Unconventional double-bended saturation of carrier occupation in optically excited graphene due to many-particle interactions"
Nature Communications 8, 15042 (2017)

J. C. König-Otto, Yongrui Wang, Alexey Belyanin, C. Berger, W. A. de Heer, M. Orlita, A. Pashkin, H. Schneider, M. Helm, S. Winnerl:
“Four-wave mixing in Landau-quantized graphene”
Nano Lett. 17, 2184 (2017)


J. C. König-Otto, M. Mittendorff, T. Winzer, F. Kadi, E. Malic, A. Knorr, C. Berger, W. A. de Heer, A. Pashkin, H. Schneider, M. Helm, S. Winnerl:
„Slow noncollinear Coulomb scattering in the vicinity of the Dirac point in graphene"
Phys. Rev. Lett. 117, 087401 (2016)

 A. Singh, S. Winnerl, J. C. König-Otto, D. R. Stephan, M. Helm, H. Schneider:
“Plasmonic efficiency enhancement at the anode of strip line photoconductive terahertz emitters”
Optics Express 24, 22628 (2016)

Shengqiang Zhou, Lin Li, Ye Yuan, A. W. Rushforth, Lin Chen, Yutian Wang, R. Böttger, R. Heller, Jianhua Zhao, K. W. Edmonds, R. P. Campion, B. L. Gallagher, C. Timm, M. Helm:
„Precise tuning of the Curie temperature of (Ga,Mn)As-based magnetic semiconductors by hole compensation: Support for valence-band ferromagnetism”
Phys. Rev. B 94, 075205 (2016)

L. Balaghi, T. Tauchnitz, R. Huebner, L. Bischoff, H. Schneider, M. Helm, E. Dimakis:
"Droplet-confined alternate pulsed epitaxy of GaAs nanowires on Si substrates down to CMOS-compatible temperatures"
Nano Lett. 16, 4032 (2016)

S. Prucnal, F. Liu, M. Voelskow, L. Vines, L. Rebohle, D. Lang, Y. Berencén, S. Andric, R. Böttger, M. Helm, S. Zhou, W. Skorupa:
"Ultra-doped n-type germanium thin films for sensing in the mid-infrared"
Scientific Reports 6, 27643 (2016)

D. R. Stephan, J. Bhattacharyya, Y. Huo, O. G. Schmidt, A. Rastelli, M. Helm, H. Schneider:
„Inter-sublevel dynamics in single InAs/GaAs quantum dots induced by strong terahertz excitation”
Appl. Phys. Lett. 108, 082107 (2016)

K. J. Kaltenecker, J. C. König-Otto, M. Mittendorff, S. Winnerl, H. Schneider, M. Helm, H. Helm, M. Walther, B. M. Fischer:
“Gouy phase shift of a tightly focused, radially polarized beam”
Optica 3, 35 (2016)


M. Mittendorff, J. Kamann, J. Eroms, D. Weiss, C. Drexler, S. D. Ganichev, J. Kerbusch, A. Erbe, R. J. Suess, T. E. Murphy, S. Chatterjee, K. Kolata, J. Ohser, J. C. König-Otto, H. Schneider, M. Helm, S. Winnerl:
“Universal ultrafast detector for short optical pulses based on graphene”
Optics Express 23, 28728 (2015)

Xin Ou, K.-H. Heinig, R. Hübner, J. Grenzer, Xi Wang, M. Helm, J. Fassbender, S. Facsko: 
“Faceted nanostructure arrays with extreme regularity by self-assembly of vacancies”
Nanoscale 7, 18928 (2015)

F. Eßer, O. Drachenko, A. Patanè, M. Ozerov, S. Winnerl, H. Schneider, M. Helm:
“Direct determination of the electron effective mass of GaAsN by terahertz cyclotron resonance spectroscopy” 
Appl. Phys. Lett. 107, 062103 (2015)

M. Fehrenbacher, S. Winnerl, H. Schneider, J. Döring, S. C. Kehr, L. M. Eng, Y. Huo, O. G. Schmidt, K. Yao, Y. Liu, M. Helm:
“Plasmonic superlensing in doped GaAs”
Nano Lett. 15, 1057 (2015)

M. Mittendorff, F. Wendler, E. Malic, A. Knorr, M. Orlita, M. Potemski, C. Berger, W. A. de Heer, H. Schneider, M. Helm, and S. Winnerl:
„Carrier dynamics in Landau-quantized graphene featuring strong Auger scattering“ 
Nature Physics 11, 75 (2015)


Kun Gao, S. Prucnal, R. Hübner, C. Bähtz, I. Skorupa, Yutian Wang, W. Skorupa, M. Helm, S. Q. Zhou:
“Ge1-xSnx alloys synthesized by ion implantation and pulsed laser melting”
Appl. Phys. Lett. 105,  042107 (2014)

S. Prucnal, M. Glaser,  A. Lugstein, E. Bertagnolli, M. Stöger-Pollach,  S. Zhou, M. Helm,  D. Reichel,  L. Rebohle,  M. Turek,  J. Zuk,  W. Skorupa:
“III-V semiconductor nanocrystal formation in silicon nanowires via liquid-phase epitaxy”
Nano Research 7, 1769 (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)


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)


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)



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)



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)



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)



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)