Development of Quaternary InAlGaN Barrier Layer for High Electron Mobility Transistor Structures

Work by J. Jorudas et al. was recently published in the MDPI Materials journal reporting about the development of high electron mobility transistor structures based on quaternary lattice matched InAlGaN barrier layer.

The thorough study on the morphological, optical and electrical properties of the layers is accomplished aiming towards application for microwave power and terahertz plasmonic devices.

The paper is open access and is available through the link:

The work was supported by the Research Council of Lithuania under the “TERAGANWIRE” project (Grant No. S-LL-19-1), by the National Science Center of Poland (Grant No. 2017/27/L/ST7/03283), by “International Research Agendas” program of the Foundation for Polish Science co-financed by the EU under the European Regional Development Fund (Nos. MAB/2018/9), and partially supported by the Polish National Center for Research and Development through projects No. WPC/20/DefeGaN/2018 and No. TECHMATSTRATEG-III/0003/2019.

New work published concerning advantages of optical modulation in terahertz imaging for study of graphene layers

The newest study was published in Journal of Applied Physics by Rusnė Ivaškevičiūtė-Povilauskienė et al. about the advantages of optical modulation in terahertz imaging for study of graphene layers.

It was demonstrated that optical modulation together with simultaneous terahertz (THz) imaging application enables an increase in contrast by an order of magnitude, thereby illustrating the technique as a convenient contactless tool for characterization of graphene deposited on high-resistivity silicon substrates.

The technique is applied in the development and investigation of graphene-based optical diffractive elements for THz imaging systems.

The work achieved funding from Horizon 2020 program under Grant No. 823728 (DiSetCom) as well as by the Academy of Finland Flagship Programme “Photonics Research and Innovation (PREIN)” (Decision No. 320165).

The paper is open access and can be easily reached through the DOI:

Annual Table Football Championship!

Traditional THz Atelier Table Football Championship was held just before Christmas. Ten participants registered to this event to prove themself as skillful players.

Five teams were competing for the very nice looking newly established prize. The prize is introduced this year and now will pass every year to new champions.

The teams were created randomly from the list of registered players using sophisticated algorithm just before the start of the championship. It was done to avoid illegal preliminary agreements among players despite some fierce protests.

After set of games the winners were announced and the prize was awarded to Dr. Mindaugas Karaliūnas and Vladislovas Čižas team. Congratulations to the new champions!

By the way, due to COVID-19 pandemic last year table football championship was postponed until this year. Looking forward to meet at the same table next year.

Season’s Greetings!

THz Atelier team wishes you Merry Christmas and Happy New Year! Let the year of 2022 (or 12022 in Holocene calendar proposed by Cesare Emiliani) be the most fascinating and prosperous.

Lithuanian patent “Broadband high-frequency generating / amplifying device, using semiconductor superlattices” by Gintaras Valušis, Kirill Alekseev, Vladislovas Čižas, Linas Minkevičius, Natalia Alexxeva, Dalius Seliuta, Liudvikas Subačius ( LT2021567).

New principle and at the same time a new type of compact high-frequency radiation source operating at room temperature that can be placed on a semiconductor chip is suggested. It is broadband and can operate in the both GHz and THz frequency bands. Operation of the device relies on principles of the quantum optoelectronics (Esaki-Tsu nonlinearity of the quantum super-lattice), and employ drift-relaxation modes to amplify high-frequency radiation, which propagates in a semiconductor superlattice along its axis at a speed approximately 1000 times slower than the speed of light in a material. It can be realized in semiconductor superlattice with non-ohmic injection contacts of an appropriate design.

Patent No. LT2021567. At the time of writing this post some public access restrictions were implemented on this patent.

High precision parabolic quantum wells grown using pulsed analog alloy grading technique: Photoluminescence probing and fractional-dimensional space approach

New paper by M. Karaliūnas et al. “High precision parabolic quantum wells grown using pulsed analog alloy grading technique: Photoluminescence probing and fractional-dimensional space approach” reports the findings on PL characterization with the help of fractional-dimensional space approach revealed precisely grown parabolic quantum well using molecular beam epitaxy pulsed analog alloy grading technique. The study presents beautiful physics of electrons being confined in 52-nm-width parabolic quantum well and proves the validity of Khon theorem. The work was supported by European Social Fund (project No 09.3.3-LMT-K-712-02-0172) under grant agreement with the Research Council of Lithuania (LMTLT). It can be reached via DOI: 10.1016/j.jlumin.2021.118321