Semiconductor Device Materials

This unit is working on the development of novel semiconductor materials for high-frequency and power electronics. The research also focuses on developing spectroscopic techniques for studying electronic and transport properties of materials from bulk to nanoscale.

III-Nitrides for applications in the next generation of wireless communication, sensing, and power infrastructures. The research focuses on optimization of epitaxial design and properties of GaN and AlGaN device structures on SiC, GaN and AlN substrates by hot-wall MOVPE. The activity covers growth of the device structures with the main aim to minimize defect densities (dislocations and background impurities), and the design of the epi-stack targeting different functionalities, e.g. power amplification, noise, and flicker-noise, switch losses, device design, etc.

Terahertz ellipsometry and optical Hall effect. We have developed unique THz ellipsometry and magneto-ellipsometry (optical Hall effect) instrumentation at the Terahertz Materials Analysis Center. These novel techniques makes it possible to explore electronic, transport and magnetic properties and phenomena in e.g, semiconductors, nanomaterials, organic materials, which cannot be assessed by other means. Current research efforts include application of THz to FIR ellipsometry to study 2DEG in transistor and quantum structures, 2D materials, conductive polymers, proteins and biomaterials.

Ultra-wide bandgap semiconductors. Main focus is put on β-Ga2O3 for applications in high-power electronic devices with substantial efficiency gain in e.g., generation and transmission of electric power, electrification of vehicles and motor drivers. Current research efforts include development of MOVPE of β-Ga2O3 and profound understanding of phonon, free charge carrier and electronic properties in relation to microstructure of thin films and device heterstructures.

2D materials. Current research activities include using THz ellipsometry to study, understand and optimize the transport, electronic and structural properties of e.g., epitaxial graphene grown on SiC, MAXens, and BN.

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2021

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International

  • Prof. M. Schubert, University of Nebraska-Lincoln, USA
  • Prof. N. Grandjean, EPFL, Switzerland
  • Dr. S. Ruffenach, University of Montpellier, France
  • Prof. K. Kishino, Sofia University, Japan
  • Prof. W. J. Schaff, Cornell University, USA
  • Prof. Y. Nanishi, Retsumeikan University, Japan
  • Dr. T. Monteiro, University of Aveiro, Portugal
  • Prof. L.-C. Cheng, National Taiwan University, Taiwan
  • Prof. A. Yoshikawa, Chiba University, Japan
  • Prof. E. Valcheva, Sofia University, Bulgaria.
  • Prof. L. W. Tu, National Sun Yat-Sen University, Taiwan
  • Dr. H-W. Becker, Rhur University, Germany
  • Dr. K. Lorenz, ITN/IST, Portugal
  • Dr. A. Tiberj, University of Montpellier 2, France

 

 

 

Industrial collaborations

  • Dr. T. Tiwald, Dr. G. Hertzinger and Prof. J. Woollam, J.A. Woollam Co , USA - ellipsometry equipment and software
  • Dr. O. Kordina, SweGaN AB, Sweden - AlGaN, HEMTs
  • Dr. F. Allerstam, On Semiconductor, USA - high-frequency electronics
  • Dr. C.-Y. Chen, ABB, Sweden - high power electronics
  • Dr. M. Higashiwaki, Tamura Co., Japan - Ga2O3
  • Prof. R. Yakimova, Graphensic AB, Sweden - graphene
  • Prof. A. Usui, Furukawa Co., Ltd., Japan - bulk GaN

Internal

  • Prof. H. Zirath and Dr. N. Rorsman, Chalmers University - electronic devices
  • Prof. R. Yakimova - graphene
  • Dr. F. Tasnadi - ab initio calculations
  • Prof. J. Birch - novel nitride alloys
  • Dr. P. Persson - TEM
  • Prof. E. Janzen - HEMTs
  • Dr. A. Kakanakova - AlN and AlGaN
  • Prof. B. Monemar - PL and InN

External mediaShow/Hide content

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 springer.com.

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. 

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Student project

Recently Shiqui Guo has joined our group. He will spend the next few months (spring term 2021) working on his Bachelor project on graded AlGaN HEMTs. He will work closely with Ph.D. student Alexis Papamichail and focus on the characterization of the HEMTs.

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