Optoelectronic devices operated in the near- and mid-infrared range are used in sensing, telecommunication and are attractive for the intra/inter chip optical interconnection. Highly doped semiconductors like GaAs, Ge and Si are attractive for near and mid-infrared plasmonics, where the plasma frequency is controlled by the carrier concentration. The mid-infrared spectral range from 2 to 10 μm overlaps with the characteristic vibration modes of green-house gasses like NO, SO, CO2, … and C-H groups which are present in different explosives. Therefore plasmonic devices operated in mid-infrared are very attractive for monitoring of air pollutions and for the safety section.


In principle there are two basic concepts for the development of plasmonic devices: (i) the use of metal nanoparticles and (ii) ultradoped semiconductors. Our work focuses on the doping of GaAs, Ge and Si beyond the solid solubility limit. The ultra-high doping is realized by utilization strongly non-equillibrium processing like ion implantation followed by either ms-range flash lamp annealing or ns-range pulsed laser annealing. During FLA the implanted layer recrystallizes via solid phase epitaxy while the PLA causes the recrystallization via liquid phase. The material of choice is taken based on the carrier mobility and required plasma edge. For the n-doping of GaAs we use chalcogen elements (S and Te). The p-type GaAs is realized by doping with Zn. For both cases the doping above 1020 cm-3 is achieved. This allows fabrication of plasmonic devices with tunable plasma frequency down to 4 μm. The tuning of the plasma frequency in Ge based devices can be realized by the controlling of the electron concentration and by the modification of the carrier mobility via alloying of Ge with Sn.


(1) Prof. Jörg Schulze

University of Stuttgart, Germany

(2) Prof. E. Napolitani

University of Padova, Italy

(3) Prof. G. Isella

Universy of Milano, Italy

(4) Prof. Lasse Vines

University of Oslo, Norway

Related publications:

[1] Mid- and far-infrared localized surface plasmon resonances in chalcogen-hyperdoped silicon
M. Wang, Y. 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 and S. Zhou
Nanoscale (2022)

[2] Plasmonic gratings from highly doped Ge1-y Sn (y) films on Si
F. Berkmann, M. Ayasse, J. Schlipf, F. Mörz, D. Weißhaupt, M. Oehme, S. Prucnal, Y. Kawaguchi, D. Schwarz, I. A. Fischer, J. Schulze
Journal of Physics D: Applied Physics 54, 445109 (2021)

[3] In-situ ohmic contact formation for n-type Ge via non-equilibrium processing
S. Prucnal, J. Frigerio, E. Napolitani, A. Ballabio, Y. Berencén, L. Rebohle, M. Wang, R. Boettger, M. Voelskow, G. Isella, R. Hübner, M. Helm, S. Zhou, W. Skorupa
Semicond. Sci. & Tech., 32, 115006 (2017)

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


The integration of the photonic devices with silicon based microelectronic would enable faster devices with lower power consumption. Nowadays this dream can be true thanks to Ge. Intrinsic Ge is indirect band gap semiconductor but alloying with Sn, and n-type doping beyond 1020 cm-3 and/or biaxial tensile strain engineering can convert Ge into direct band gap semiconductor. A combination of Sn alloying with n-type doping and tensile strain has a potential to make stable direct band gap Ge with emission covering the telecommunication window. Moreover Ge together with Si belongs to group IV semiconductors which makes it compatible with CMOS technology. We are alloying Ge with Sn using Sn implantation followed by FLA for 3 ms. Co-implantation of Sn and P allows us to fabricate direct band gap Ge with carrier concentration above 1020 cm-3.


(1) Prof. Inga Anita Fischer

University of Cottbus, Germany

(2) Prof. J. Żuk

University of Lublin, Poland

(3) Prof. Robert Kudrawiec

Universty of Wrocław, Poland

Related publications

[1] Strain and Band-Gap Engineering in Ge-Sn Alloys via P Doping
Slawomir Prucnal, Yonder Berencén, Mao Wang, Jörg Grenzer, Matthias Voelskow, Rene Hübner, Yuji Yamamoto, Alexander Scheit, Florian Bärwolf, Vitaly Zviagin, Rüdiger Schmidt-Grund, Marius Grundmann, Jerzy Żuk, Marcin Turek, Andrzej Droździel, Krzysztof Pyszniak, Robert Kudrawiec, Maciej P. Polak, Lars Rebohle, Wolfgang Skorupa, Manfred Helm, and Shengqiang Zhou
Phys. Rev. Applied 10, 064055 (2018) | arXiv:1901.01721

[2] Ex situ n+ doping of GeSn alloys via non-equilibrium processing
S. Prucnal, Y. Berencén, M. Wang, L. Rebohle, R. Böttger, I. A. Fischer, L. Augel, M. Oehme, J. Schulze, M. Voelskow, M. Helm, W. Skorupa and S. Zhou
Semicond. Sci. & Tech., 33, 065008 (2018)

IR photodetectors

The room-temperature broadband photoresponse of silicon in the infrared region is of great interest for on-chip photonic platforms, but is fundamentally limited to the near infrared, due to the particular value of the band gap. We combine ion implantation with pulsed laser melting in a CMOS-compatible approach to introducing Te dopant into the Si crystal, at concentrations orders of magnitude above the solid solubility limit. This leads to the formation of an intermediate band in the upper half of silicon’s band gap, extending the photoresponse of Te-hyperdoped p−n photodiodes to the midinfrared range.


(1) Dr. E. García-Hemme

Univ. Complutense de Madrid, Spain

Related publications

[1] Room-temperature extended short-wave infrared GeSn photodetectors realized by ion beam techniques 
Shuyu Wen, Mohd Saif Shaikh, Oliver Steuer, Slawomir Prucnal, Jörg Grenzer, René Hübner, Marcin Turek, Krzysztof Pyszniak, Sebastian Reiter, Inga Anita Fischer, Yordan M. Georgiev, Manfred Helm, Shaoteng Wu, Jun-Wei Luo, Shengqiang Zhou, Yonder Berencén
Appl. Phys. Lett. 123, 081109 (2023)

[2] On-chip lateral Si:Te PIN photodiodes for room-temperature detection in the telecom optical wavelength bands 
Mohd Saif Shaikh, Shuyu Wen, Mircea-Traian Catuneanu, Mao Wang, Artur Erbe, Slawomir Prucnal, Lars Rebohle, Shengqiang Zhou, Kambiz Jamshidi, Manfred Helm, and Yonder Berencén
Optics Express 31,pp. 26451-26462 (2023)

[3] Silicon-based Intermediate-band Infrared Photodetector realized by Te, Hyperdoping
M. Wang, E. García-Hemme, Y. Berencén, R. Hübner, Y. Xie, L. Rebohle, C. Xu, H. Schneider, M. Helm, S. Zhou
Advanced Optical Materials 9, 2001546 (2021)

[4] Extended Infrared Photoresponse in Te-Hyperdoped Si at Room Temperature
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, and Shengqiang Zhou
Phys. Rev. Applied 10, 024054 (2018)

[5] Room-temperature short-wavelength infrared Si photodetector
Y. Berencén, S. Prucnal, F. Liu, I. Skorupa, R. Hübner, L. Rebohle, S. Zhou, H. Schneider, M. Helm, W. Skorupa
Scientific Reports 7, 43688 (2017)