News - Semiconductor Device Materials

Chapter on Phonon Properties published in book Gallium Oxide

In this chapter, written by members of our team we present and discuss the complete set of infrared-active phonon modes in monoclinic-symmetry crystal modification gallium oxide. This chapter attempts to summarise the current state of knowledge about the optical phonon mode propoerties and their coupling with free charge carriers in gallium oxide with monoclinic crystal structure.

You can find the book at

April 2019 - Inside front cover in Journal of Materials Chemistry C

Our paper on the anomalous optical conductivity dispersion of electrically conducting polymers determiend by ultra-wide spectral range ellipsometry combined with a Drude-Lorentz model is selected as inside front cover in the April issue of Journal of Materials Chemistry C.

J. Mater. Chem. C, 2019,7, 4350-4362.

April 2019 - Eva Bittrich from Leibniz Institute of Polymer Research Dresden is visiting

Eva Bittrich from Leibniz Institute of Polymer Research Dresden is visiting THeMAC for a week. She is working on applying far-infrared and terahertz spectroscopic ellipsometry to study the H-bonding in thin polycristalline films of ellagic acid and other semiconducting films of small organic molecules. Eva presented a Faculty seminar on Nanostructured organic thin films for biosensing and energy harvesting. We are looking forward to this new exciting collaboration in polymer research.

March 2019 - The 2nd Swedish Terahertz Workshop

On 28th of March the Terahertz Materials Analysis Center (THeMAC) organized the 2nd Swedish Terahertz Workshop. About 40 scientists from Stockholm University, Chalmers University of Technology, KTH, Gothenburg University, University of Nebraska - Lincoln, US Naval Research Lab, State University of New Mexico, University of California at Santa Barbara, University of North Carolina Charlotte, NEST at Istituto Italiano di Tecnologia  and Linköping University gathered together to discuss THz materials research and collaborative efforts within THeMAC.  The workshop was organized in four sessions and covered a broad variety of materials, techniques and applications including THz Components and InfrastructuresNew Materials and PhenomenaBio Applications and Semiconductors and MetamaterialsDetailed program can be found here.

March 2019 - Nerijus Armakavicius is awarded PhD degree in Semiconductor Materials

We congratulate our PhD student Nerijus Armakavicius for being awarded PhD degree in Semiconductor Materials. On 27th of March Nerijus defended his thesis with an excellent presentation. We are grateful to the Faculty opponent, Prof. Stefan and the Evaluation Board members, Prof. Åsa Haglund, Prof. Saulius Marcikanvicius and Docent Hellena Rodilla for their hard and thorough work.

March 2019 - Nerijus Armakavicius PhD thesis nailing

On 5th of March Nerijus Armakavicius nailed his PhD thesis. The public defence will take place on 27th of March.

March 2019 - We welcome Muhammad Nawaz as an adjunct professor

From 1st of March we welcome Muhammad Nawaz from ABB as an Adjunct Professor in the Competence Center for III-Nitride Technology, C3NiT - Janzén

October 2018 - We welcome Rosalia Delgado and Alexis Papamichail as new PhD students in C3NiT

Rosalia will work on elaborating thick Ga(Al)N layers by hot-wall MOCVD on bulk GaN and nanowire templates for power switches and diodes. Alexis will develop p-type doping of Ga(Al)N, in-situ and via Mg implantation, trench regrowth, and his project includes also characterization/optimization of transport properties.

September 2018 - We welcome Dat Tran, a new PhD student in C3NiT

Dat's PhD project involves investigation and optimization of thermal and electrical properties of III-N epilayers and heterostructures for rf and power devices.

June 2018 - Nerijus Armakavicius is recipient of the 2018 E-MRS Graduate Student Award

Nerijus wins the 2018 E-MRS Graduate Student Award for his work on applying THz ellipsometry and optical Hall effect to measure anisotropic mobility in epitaxial graphene.

June 2018 - Vanya Darakchieva receives PI support from AFM

Vanya recieves support as a principle investigator of the Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials at Linköping University for the period 1/2019 - 12/2021.

April 2018 - Alyssa Mock is the recipient of the 2018 UNL College of Engineering Outstanding Doctoral Dissertation Award

March 2018 - Vanya Darakchieva recieves a framework grant for Strategic Research on Materials for Energy Applications

The Swedish Foundation for Strategic Rsearch, SSF awards 35 MSEK for 2018-2022 to LiU in partnership with Chalmers, Lund University, SweGaN, Hexagem, On Semiconductor, and ABB for the project Low-defect-density III-Nitrides for Green Power Electronics. We will develop low-dislocation-density nanowire-based GaN and AlGaN wafers and subsequent homoepitaxy of device structures for vertical Ga(Al)N on Ga(Al)N junction barrier diodes and switches in the 600 V - 5 kV range and beyond. The project will be kicked-off on 8th of May at Chalmers.

Next generation semiconductor materials

January 2017 - Vanya Darakchieva recieves a consolidator grant by the Swedish Research Council

Vanya Darakchieva receives a 12 MSEK consolidator grant by the Swedish Research Council (VR) for her project TeraNextTerahertz optical Hall effect in materials for next generation high-speed and high-power electronics. The purpose of the grant is to provide the most outstanding young scientists in all areas of natural sciences, medicine, social sciences and education in Sweden, the opportunity to consolidate and broaden their research efforts. TeraNext focuses on THz optical Hall effect developments and comprehensive investigations of free charge carrier properties in conjunction with state-of-the-art growth of group-III nitrides, graphene and Ga2O3.

November 2016 - Chamseddine Bouhafs is a awarded PhD degree in Semiconductor Materials

We congratulate our PhD student Chamseddine Bouhafs for being awarded PhD degree in Semiconductor Materials. On 29th of November Chams defended his thesis with an excellent presentation. We are grateful to the Faculty opponent, Prof. Jacek Baranowski and Evaluation Board members, Prof Kenneth Jarrändahl, Prof. Alexander Soldatov, Prof. Avgust Jurgens and Prof. Martin Magnusson for hard and thorough work.

September 2016 - We welcome Prof. Mathias Schubert as a guest professor

We welcome our long term collaborator Mathias Schubert as a guest professor in the Terahertz Materials and Advanced Ellipsometry group. Mathias is recruited via the strategic funds of AFM. He will work together with our group and colleagues at AFM towards expanding the capabilities of the Terahertz Materials Analysis and Imaging Center with novel imaging ellipsometry infrastructure. We are looking forward to the exciting new developments of Anisotropic Contrast Imaging Mcroscopy and THz imaging.

May 2016 - Vannya Darakchieva is appointed Adjunct Professor at the University of Nebraska-Lincoln

March 2016 - The Swedish Terahertz Workshop and THeMAC Inauguration

On 14th of March we organized the Swedish Terahertz Workshop in relation to the Terahertz Materials Analysis Center (THeMAC) inauguration. About 40 scientists from Uppsala University, Chalmers University of Technology, KTH, Luleå University, Bårås University and Linköping University gathered together to discuss THz materials research and get acquaintance with the unique capabilities of THeMAC. Prof. Bruno Gompf from Stuttgart University set the scene with an exciting talk on THz ellipsometry and related applications. The workshop continued with three sessions on diverse materials issues and characterization challenges including epitaxial graphene, organic polymers, nanowires, bioinspired polarizers, sensing single molecules, neutron ellipsometry and THz plasmonics.  A culmination was reached in the early afternoon when we all visited THeMAC which sprang an avalanche of ideas for future collaborative initiatives. The excitement after the intense day was quite to relaxed discussions over a glass of champagne which concluded the workshop.

A short article by Åke Hjelm with beautiful photos from the lab by Thor Balkhed can be found here

January 2016 - One step closer to our dream - Vanya Darakchieva receives an Infrastructure Fellow Award from the Swedish Foundation for Strategic Research

Vanya Darakchieva receives 15 MSEK Infrastructure Fellow award from the Swedish Foundation for Strategic Research to build upon her current developments of the only Terahertz ellipsometer in Europe and establish a central open-access facility at IFM, Linköping University: The Terahertz Materials Analysis Center (THeMAC). The facility is world-unique and will enable for the first time to explore low-energy excitation phenomena in condensed and soft matter, thus opening new research fields in material science and engineering, physics and life sciences.

August 2015 - Record mobility in AlGaN/GaN HEMT measured by THz cavity-enhanced optical Hall effect

A record room-temperature mobility of 2332 cm2/V.s. has been measured for the 2-dimensional electron gas in AlGaN/GaN HEMTs using THz cavity-enhanced optical Hall effect. Our abstract on the subject was accepted as a late news talk at the 11th International Conference on Nitride Semiconductors ICNS-11 in Beijing.

August 2015 - Mengyao Xie from Universidad Politécnica de Madrid is visiting

Mengyao Xie, a post doc fromUniversidad Politécnica de Madrid and a former member of our group, is visiting for 1 month. She is working on determination of free-charge carrier properties of InGaN films and nanocolumns by infrared and THz spectroscopic ellipsometry.

July 2015 - It's working, it's working....

We are very excited to demonstrate the first measurements using our new THz ellipsometer. We have successfuly measured THz cavity-enhanced optical Hall efect in one monolayer graphene grown on Si-face 4H-SiC.

June 2015 - Sean Knight from the University of Nebraska-Lincoln is visiting

Sean Knight, a master student from University of Nebraska-Lincoln is visitting for 1 month. He is working together with Tino Hofmann, Chams Bouhafs, Vallery Stanishev, Nerijus Armakavicius and Philipp Kuehne on in-situ measurements of ambient effects on the free-charge carrier properties of graphene using our new THz ellipsometer.

May 2015 - Professor Mathias Schubert recieves the Honorary Doctor Degree from Linköping University

Prof. Mathias Schubert from University of Nebraska-Lincoln (UNL), a world-leading expert in the fields of optics and materials science and a long-term collaborator with our group, receives the Honorary Doctor Degree from Linköping University.

Mathias Schubert has made seminal contributions to the fields of spectroscopy, condensed matter physics and materials science and technology. He has pioneered infrared, far-infrared and terahertz spectroscopic ellipsometry, and invented the optical Hall effect. These techniques helped his team and researchers world-wide to develop and implement novel materials for blue and white light emitting diodes, organic solar cells, high-speed processor technologies and bio-, and chemical sensing.  Mathias Schubert has since 2000 participated along with researchers from our group in several research projects and large initiatives that resulted in numerous doctoral theses, scientific papers and patents. He has played a key role in the establishment of the infrared and terahertz ellipsometry laboratories at Linköping University, and the exchange of students and senior researchers between Sweden and USA. Thanks to the fruitful collaboration with the group of Prof. Schubert, Linköping University is currently recognized as one of the leading centers on spectroscopic ellipsometry in the world.

March 2015 - Professor Tino Hofmann is named Marie Curie Fellow and VINNMER Fellow.

The Fellowship is supported by the EU Marie Curie Action and Sweden's innovation agency VINNOVA to progress tight collaboration between the University of Nebraska-Lincoln, the University of Linköping, Sweden, and private enterprises in the US and Sweden. The goal of this collaboration between world-leading experts in growth and characterization of graphene and group-III nitride materials in Sweden with experts in the Center of Nanohybrid Functional Materials at UNL is to design, manufacture, and characterize graphene-metal nanostructure hybrid materials for novel terahertz frequency devices.Tino Hofmann will join our group from March 2015.

February 2015 - Philipp Kuehne recieves the 2015 Folsom Distinguished Doctoral Dissertation Award

January 2014 - Vanya Darakchieva receives a Future Research Leaders award from the Swedish Foundation for Strategic Research

Vanya Darakchieva receives 10 MSEK Future Research Leaders award from the Swedish Foundation for Strategic Research (SSF) for her project THz ellipsometry of advanced materials for high-speed electronics. The goal of the project is to build a unique THz ellipsometry instrumentation and use it to explore the mechanisms that generate and control the free-charge carrier properties in epitaxial layers of In(Ga,Al)N and graphene. The research aims at enabling the desired transport properties in these materials in order to achieve substantial advance towards high-speed and THz-frequency large scale processor technologies. The THz ellispometer is a revolutionary instrument and will be the only one of its kind in Europe. It is a noncontact, non-destructive method of measuring electrical transport properties with substantial advantages over conventional electrical measurements. It allows differentiation of electronic transport properties of differently conductive channels in multi-layered or inhomogeneous samples, with no physical contact which can result in surface damage or sample contamination. The new ellipsometer will make possible the measurement of THz transistor devices at their operating frequencies. The THz ellipsometry has greater potential to advance our understanding of transport properties not only in graphene but, for example, in multiferroic tunnel structures, magnetoelectric heterostructures, ferromagnetic and ferroelectric polymer structures, magnetic and piezoelectric hybrid nanostructures and solar cell materials.

For more information click here.