Institute of Applied Research

Sukurta: 30 July 2017

3 Saulėtekio, LT-10257 Vilnius
Tel. 223 4483, fax. 223 4482
E-mail:
www http://www.tmi.vu.lt

Director – Prof. Habil. Dr. Saulius Antanas Juršėnas

STAFF

35 research fellows (incl. 27 holding research degree).

Contract Research group
Group for Research of Photoelectrical Phenomena
Lighting Research group
Nitride Epitaxial Technology and Device Research group
Organic Optoelectronics Research group
Semiconductor Photonics group

RESEARCH AREAS

Investigation of Novel Organic and Inorganic Functional Materials and Structures
Development, Characterization, and Interdisciplinary Application of Advanced Electronic and Optoelectronic Devices

DOCTORAL DISSERTATIONS MAINTAINED IN 2016

J. Jurkevičius. Photoluminescence efficiency in wide-band-gap III-nitride semiconductors and their heterostructures.
J. Pavlov. Detector structures on defect-rich silicon and wide band-gap semiconductors.
I. Reklaitis. Advanced III-nitride-based optoelectronic devices: fabrication and characterization.
V. Rumbauskas. Peculiarities of carrier scattering and thermal emission in large fluence irradiated silicon.

CONTRACT RESEARCH GROUP

29 M. K. Čiurlionio, LT-03100 Vilnius
Tel. 265 1797, fax 233 5648
E-mail:

Head – Dr. Arūnas Samuilis

STAFF

Senior research fellow: Dr. A. Samuilis (part time).
Research fellow: Dr. A. Konstantinov (part-time).
Senior engineers: V. Dadurkevičius, D. Ralys, F. Ralienė, J. Vaičiulis (all part-time).

RESEARCH INTERESTS

Artificial intelligence in various Lithuanian language computer implementations: e.g. machine translation, search systems, intelligent dictionaries, text parsing and data mining
The development of the dictionary of contemporary Lithuanian

RESEARCH PROJECTS CARRIED OUT IN 2016

Projects Supported by University Budget

Development of General Language Resources and Technologies. Dr. A. Samuilis. 2016–2017.

The group participates in the build-up of the International Research Infrastructure - the Common Language Resources and Technology Infrastructure at the European Research Infrastructure Consortium (CLARIN ERIC).
The results of the year 2016:
1. The stemming analysis tool for Lithuanian texts has been designed and used for indexing and searching of Lithuanian texts.
2. The morphological database for Lithuanian has been expanded by more than 18,000 new lemmas comprising: last names, over 4,000 new lemmas, about the same amount of the last names of men, women and girls; the names of actions (ending with -ymas), about 800 lemmas; adjectives with negative prefixes (ne-, nebe-), about 1500 lemmas; negative verbs (with prefixes ne-, nebe-), about 7,000 lemmas; reflexive verbs (ending with -tis), about 700 lemmas; negative reflexive verbs (with prefixes nesi-, nebesi-), about 700 lemmas; verbs with prefixes te-, tebe-, about 3,000 lemmas; other words, about 450 lemmas of different parts of speech.
3. An expanded database of the Lithuanian language morphology and grammar containing inflexion rules and dictionaries has been presented in the open-source Hunspell format.
4. Documents and recommendations containing legal questions concerning CLARIN LT have been collected, summarized and prepared for publication; the harmonization of legal issues between CLARIN ERIC and CLARIN LT has been ensured; legal advices were given to the national consortium and the national coordinator.

GROUP FOR RESEARCH OF PHOTOELECTRICAL PHENOMENA

3 Saulėtekio, LT-10257 Vilnius,
Tel. 223 4480, fax 223 4482
E-mail:

Head – Prof. Habil. Dr. Eugenijus Gaubas

STAFF

Chief research fellows: Prof. Habil. Dr. E. Gaubas, Prof. Emeritus Habil. Dr. J. V. Vaitkus, Prof. Habil. Dr. V. Kažukauskas (part-time).
Senior research fellow: Dr. T. Čeponis.
Research fellows: Dr. J. Pavlov, Dr. V. Rumbauskas, Dr. A. Mekys (part-time), Dr. E. Žąsinas (part-time).
Junior research fellow: D. Meškauskaitė.
Doctoral student: D. Meškauskaitė.
Engineers: L. Deveikis, V. Vertelis.
Tecnitian: K. Pūkas.

RESEARCH INTERESTS

Investigation of native and ionizing radiation induced defects and micro-inhomogeneities in semiconductor materials and device structures
Carrier transport phenomena in organic materials and solar cell structures
Development of measurement technologies and instrumentation for the in situ characterization of material and device structures under heavy irradiations by hadrons
Development of measurement techniques for comprehensive characterization of photo-sensors, particle detectors, light emitting diodes and solar-cells
Spectroscopy of deep levels in wide-gap semiconductors as GaN and different technology diamond
Dosimetry of large fluence irradiations
Organic material (alanine) based dosimetry
Wide –gap material scintillators for detection and dosimetry of hadron irradiations

RESEARCH PROJECTS CARRIED OUT IN 2016

Projects Supported by University Budget

Creation, Research and Application in Optoelectronics of the Promising Semiconductor Structures /Investigations in Semiconductor Material Science and Development of Specific Research Techniques. Prof. Habil. Dr. E. Gaubas. 2016.

Project is addressed to development of measurement techniques by combining the electrical and spectral characteristics of wide–gap semiconducting materials such as GaN, and synthetic diamond. The pulsed photo-ionization spectroscopy technique using microwave probes combined with spectroscopy of carrier recombination and trapping centres using microwave probed photoconductivity transients have been developed for inspection of deep levels ascribed to technological and radiation induced defects in wide-gap semiconductors. The in situ and ex-situ variations of the radiation induced photo-ionization, of barrier and storage capacitance recorded by pulsed capacitance technique and time-resolved luminescence spectra have been examined. The profiling techniques for analysis of the current transients in junction and capacitor type detectors have been developed, and these techniques were applied for evaluation of the operation performance of photo- and particle sensors. Parameters of detectors, such as transit time, diffusion time and polarization recovery time have been extracted for sensors of various configurations. The origin of the prevailing radiation defects in GaN materials of different technology have been revealed by combining ESR, absorption, Raman scattering and luminescence spectroscopy techniques.

Main publications:

Gaubas, E., Simoen, E., Vanhellemont, J. 2016. Review - Carrier lifetime spectroscopy for defect characterisation in semiconductor materials and devices. ECS J. Solid State Sci. Technol., vol. 5, p. 3108–3137.

Gaubas, E., Ceponis, T., Meskauskaite, D., Simoen, E. 2016. Comparative study of current transients in HPHT and CVD diamond capacitor-sensors. ECS J. Solid State Sci. Technol., vol. 5, p. 3101–3107.

Development of technologies for high energy radiation detectors and means for passivation of radiation defects . Prof. Habil. Dr. E. Gaubas. 2016.

Project is addressed to design of the specific detection regimes by combining the electrical and scintillation response in detectors made of wide–gap semiconducting materials such as GaN, CdS, and synthetic diamond. Tentative detectors of various configurations have been designed and fabricated. The pulsed photo-ionization spectroscopy and combined with spectroscopy of carrier recombination and trapping centres using microwave probed photoconductivity transients have been applied for inspection of deep levels ascribed to technological and radiation induced defects in wide-gap semiconductors. Parameters of detectors, such as transit time, diffusion time and polarization recovery time have been extracted for sensors of various configurations. The spectra of the thermal- and photo-ionization of traps have been examined in GaN and diamond structures by combining the pulsed photo-ionization, DLTS and time-resolved photoluminescence spectroscopy techniques. The role of radiation defect clusters and point complexes, aggregated through large density of radiation induced vacancy and interstitial defects, was also considered by the comprehensive study of recombination characteristics within FZ and MCz Si structures irradiated with high energy electrons, pions and protons. Formation of deep levels attributed to multi-vacancy structures in Si and GaN have been modelled. Tentative investigations of DLTS spectra with spectral peaks ascribed to radiation clusters have been performed. These results were correlated with pulsed photo-ionization spectra and with variations of the temperature dependent carrier trapping lifetime in the same materials and samples. The ESR spectra ascribed to clusters of radiation defects have also been examined in heavily irradiated Si. The possible ways for passivation of radiation defects using heat treatments at elevated temperatures were researched and the most promising passivation regimes have been determined.

Main publication:

Gaubas, E., Ceponis, T., Vaitkus, J.V., Fadeyev, V., Ely, S., Galloway, Z., Sadrozinski, H.F.-W., Christophersen, M., Phlips, B.F., Gorelov, I., Hoeferkamp, M., Metcalfe, J., Seidel, S. 2016. Study of surface recombination on cleaved and passivated edges of Si detectors. Semicond. Sci. Technol., vol. 31, 035003.

Organic Optoelectronics/ organic material dosimeters for detection of high energy radiations of wide spectrum. Prof. Habil. Dr. E. Gaubas. 2016.

Project is addressed to research of the combined dosimeters, using organic (alanine) and inorganic (Si) materials, for detection of wide spectrum (X-ray, high energy hadrons and electrons) radiations.
The ESR spectrometry of stable free radicals in alanine, induced by penetrative X- and γ-rays as well as neutron and stopped proton irradiations covering dose range from a few Gy to a few of MGy, has been performed in order to create the generalized calibration function for the wide range dosimetry. The simulations based on the cumulative generation of ESR active stable radicals R1, R2 and R3 enabled us to derive the generalized calibration model ascribed to irradiation fluence from 10¹⁰ to 2X10¹⁶ particle/cm2 normalized using 1 MeV neutron equivalent. The method for spectral resolution by using tandem dosimeters has been proposed and approved. The tandem dosimeters, made of alanine-Si detectors, have been fabricated and tested.

Main publication:

Čeponis, T., Gaubas, E., Venius, J., Cicinas, A., Callens, F., Kusakovskij, J., Vrielinck, H., Mizohata, K., Raisanen, J., Tikkanen, P. 2016. ESR spectroscopy of alanine impacted by high energy irradiations for wide range dosimetry. Lith. J. Phys., vol. 56, p. 49–54.

National Research Projects

Research Council of Lithuania. Development of the MOCVD GaN Based Technology for Fabrication of Position and Spectrum Selective Detectors of Ionizing Radiations (No. LAT-01/2016). Prof. Habil. Dr. E. Gaubas. 2016– 2018.

The project is addressed to development of fabrication technology of the position and radiation spectrum selective sensors made of MOCVD GaN and capable to simultaneously detect the electrical and optical signals in registration of ionizing radiations such as X- and gamma-rays as well as to operate as dosimeters of the accumulated irradiation under long term functioning of sensors. During implementation of the project, several problems are foreseen to be solved, as: development of technology of the MOCVD GaN epi-layer growth on sapphire substrates with enhanced epi-layer thickness and reduced density of extended defects; development of technology in formation of mesa structures with relevant sensor structure edges by combining the laser ablation and plasma etching techniques; development of metallization technology in formation of Schottky and blocking contacts by combining various metal deposition techniques; development of the externally governed, low gain avalanche detectors with internal amplification for registration of small electrical signals induced by ionizing radiations; development of the read-out techniques for simultaneous registration of optical and electrical signals; simulation of signal formation regimes by combining steady-state and dynamic models; characterization of steady-state and pulsed electrical signals generated by different type detectors under continuous-wave and pulsed irradiation by electromagnetic waves in wide spectral and intensity range in order to estimate sensitivity and operation diapason of the fabricated sensors; design of the formation of pixel and strip-type sensors and their deployment within MOCVD GaN substrate area to produce a position sensitive sensor array. The capacitor type and Schottky diode sensors will be combined in production of test structures. Such a technology is preferential bypassing the material doping procedures in production of a device structure.

Main publications:

Gaubas, E. Ceponis, T. Kuokstis, E. Meskauskaite, D. Pavlov, J. and Reklaitis, I. 2016. Study of charge carrier transport in GaN sensors. Materials, vol. 9, p. 293.

Gaubas, E., Ceponis, T., Meskauskaite, D., Grigonis, R., Sirutkaitis, V. 2016. Spectroscopy of defects in HPHT and CVD diamond by ESR and pulsed photo-ionization measurements, Journal of instrumentation, doi: 10.1088/1748-0221/11/01/C01017.

European COST Action MP1307: Stable Next-Generation Photovoltaics: Unraveling Degradation Mechanisms of Organic Solar Cells by Complementary Characterization Techniques (Stablenextsol). Prof. Habil. Dr. V. Kažukauskas. 2014–2018.

European COST Action MP1406: Multiscale in Modelling and Validation for Solar Photovoltaics (Multiscalesolar). Prof. Habil. Dr. V. Kažukauskas. 2015–2019.

Projects Supported by the Lithuanian Academy of Science

Project: Investigation of Radiation Defects in Si Structures and their Application for the Monitoring of Ionizing Radiation (No. MA- CERN-JV). Prof. Habil. Dr. J.V. Vaitkus. 2016.

Project is devoted to research of the magnetogalvanic effects and carrier transport characteristics in the irradiated Si structures.

Main publication:

J. V. Vaitkus, A. Mekys, V. Rumbauskas, J. Storasta. 2016. Neutron irradiation influence on electron mobility and compensation of dark conductivity in silicon crystals. Lith. Journ. Phys., vol. 56, no. 2, p. 102–110, doi: 10.3952/physics.v56i2.3306.

Project: Cryogenic Radiation Detectors (No. MA-CERN-EG). Prof. Habil. Dr. E. Gaubas. 2016.

Project is devoted to research of various type radiation detectors.

Main publications:

Rumbauskas, V., Meskauskaite, D., Ceponis, T., Gaubas, E. 2016. Anneal induced transforms of radiation defects in heavily electron irradiated Si diodes. J. Instrum. 11, vol. 11, doi: 10.1088/1748-0221/11/09/P09004.

International Science Programmes, Projects and Contracts

H2020 Project AIDA-2: Advanced European Infrastructures for Detectors at Accelerators. Prof. Habil. Dr. J.V.Vaitkus, Prof. Habil. Dr. G. Tamulaitis. 2015 –2018.

VU WP (the GROUP FOR RESEARCH OF PHOTOELECTRICAL PHENOMENA) Project is devoted to search and investigations of the simple and cheap technology Si wafers for fabrication of dosimeters exploited in dose-reading using VUTEG-5-AIDA instrument.

CERN RD39 Collaboration program: Cryogenic Tracking Detectors. Dr. J. Harkonen (Finland) and Dr. Zh. Li (USA).

Vilnius group project: Free Carrier Lifetime in Irradiated Si. Prof. Habil. Dr. J.V.Vaitkus, Prof. Habil. Dr. E. Gaubas. 2002–2015.

Project is devoted to the study of the radiation hardness of Si material and device structures by microwave probed photoconductivity transients, pulsed capacitance and carrier drift induced current measurements.

CERN RD50 Collaboration program: Radiation Hard Semiconductor Devices for Very High Luminosity Colliders. Dr. M. Moll. Contribution to the program: Materials Characterization.

Analysis of radiation defect parameters by means of extrinsic photoconductivity spectra analysis, by lifetime dependence on the hadron irradiation fluences. Combined investigations of current, capacitance and photoconductivity transients in heavily irradiated material and detector structures.

Bilateral Vilnius University-IMEC (Leuven, Belgium) collaboration agreement. This project is addressed to characterization of the GaN on Si materials.

MAIN R&D&I (RESEARCH, DEVELOPMENT AND INNOVATION) PARTNERS

Centre of Physical and Technological Sciences (Lithuania)
CC ELMIKA (Lithuania)
CC Vilniaus Ventos Puslaidininkiai (Lithuania)
CC STANDA (Lithuania)
Santa Cruz Institute for Particle Physics (USA)
University of California Santa Cruz (USA)
A net of partners created by CERN RD39 and RD50 collaboration programmes include more than 50 institutions in 19 countries

OTHER SCIENTIFIC ACTIVITIES

Prof. Habil. Dr. J.V.Vaitkus –

chairman of the Division of Physics of the Lithuanian Academy of Sciences;
Fellow of the Institute of Physics (UK);
President of the Lithuanian Physical Society;
vice-chairman of CERN RD50 collaboration board;
member of CERN RD39 collaboration board;
deputy-editor of the Lithuanian Journal of Physics; member of the international advisory board;
member of the Council of European Physical Society and general assembly of the IUPAP;
editorial board member of the journal Material Science (Medžiagotyra);
international advisory board member of the journal Physical Surface Engineering (Ukraine);
steering committee member of ROC-Lithuania-Latvia Foundation;
advisor to the Committee of Professional Qualification, European Physical Society.

Prof. Habil. Dr. V. Kažukauskas –

board member of Deutsch-Baltisches Hochschulkontor;
editorial board member of the World Scientific Journal;
President of Lithuanian DAAD Club (DAAD – German Academic Exchange Service);
member of the project selection committee of Georgian Shota Rustaveli National Science Foundation (SRNSF).

LIGHTING RESEARCH GROUP

3 Saulėtekio, LT-10257 Vilnius
Tel. 223 4474, fax. 223 4482
E-mail:

Head – Dr. Pranciškus Vitta

STAFF

Senior research fellows: Dr. P.Vitta, Dr. R. Vaicekauskas (part time).
Research fellow: Dr. A. Novičkovas (part-time).
Junior research fellows: A. Petrulis, A. Zabiliūtė-Karaliūnė.
Engineer staff: V. Čižas, H. Dapkus, J. Aglinskaitė, M. Budriūnas.
Doctoral students: D. Meškauskas, A. Petrulis, A. Zabiliūtė-Karaliūnė.

RESEARCH INTERESTS

Characterization, optimization and applications of light-emitting diodes and their systems
Lighting systems with advanced colour rendition control for general and niche lighting
Lighting systems for vegetable growth with improved nutritional quality
Intelligent solid-state lighting systems for outdoor lighting

RESEARCH PROJECTS CARRIED OUT IN 2016

Projects Supported by University Budget

Solid-State Lighting Technologies. Dr. P. Vitta. 2016–2018.

An extended study of charge-carrier localization and delocalization in blue and green InGaN light-emitting diode (LED) test structures has been performed. Using the frequency-domain lifetime measurement (FDLM) technique based on direct harmonic modulation of photoluminescence excitation in the frequency range from 1 Hz to 100 MHz, carrier lifetimes were estimated at scales spanning from milliseconds to nanoseconds. A higher degree of carrier delocalization was observed for the blue compared with the green light-emitting structure, providing qualitative insight into disorder, which is tentatively assigned to spatial fluctuations of the indium concentration in the quantum wells.

Main publication:

Reklaitis, I., Kudzma, R., Miasojedovas, S., Vitta, P., Zukauskas, A., Tomasiunas, R., Pietzonka, I., Strassburg, M. 2016. Photoluminescence decay dynamics in blue and green InGaN LED structures revealed by the frequency-domain technique. J. Electron. Mat., vol. 45 (7), p. 3290–3299.

The nonmonotonous variation of photoelectrical properties of commercial AlGaInP LEDs during the aging process was studied. The light-generated current and short-circuit photocurrent were found to drop by the factors of 2 and 1.5, respectively, after about 3 h of aging at the rated forward current of 1400 mA with subsequent recovery and stabilization within similar to 1000 h of aging. The observed temporal variation of the photoelectrical properties was attributed to the interplay of recombination-enhanced growth and annealing of defects responsible for non-radiative recombination and photoconductivity in the active and cladding layers of the LEDs, respectively.

Main publications:

Meskauskas, D., Dabasinskas, L., Zukauskas, A. 2016. Effect of aging on the photoelectrical properties of AlGaInP LEDs. IEEE Trans. Electron. Dev., vol. 63 (7), p. 2815–2819.

National Research Projects

Research Council of Lithuania. Scientist initiative project: Colour Restoration in Cultural Heritage Objects Using Solid-State Lighting, led by Dr. R. Vaicekauskas at Faculty of Mathematics and Informatics. 2015–2017.

The objects of cultural heritage, such as paintings, textiles, and jewellery, are damaged by the environmental factors over the time. The restoration of these objects, which aims at revealing the original visual appearance, is highly resource demanding task that is often associated with destructive physical impact. The idea of the Project HeriLED is to investigate the possibility of recreating the original appearance of an damaged object using a lighting device having appropriate spectral power distribution that is comprised of light-emitting diodes (LEDs), when the assumed original visual appearance is available from an undamaged fragment (e.g. back side of the tapestry).

International Research Projects

7^th Framework Programme. Coordination and Support Action. Accelerate SSL Innovation for Europe (SSL-erate) (No. 619249). Representative of Vilnius University Prof. Habil. Dr. A. Žukauskas. 2013–2016.

The preparation of the introductory map of green business opportunities for solid-state lighting (SSL) was contributed. The local industry and other green business stakeholders were contacted to discuss the SSL deployment in terms of sustainability and meaningfulness. The preparation of the introductory and situation analysis reports on lighting for health and well-being in Smart Cities was contributed. Presentation at a workshop for Lithuanian lighting designers to support awareness raising and implementation was given.

MAIN R&D&I (RESEARCH, DEVELOPMENT AND INNOVATION) PARTNERS

JSC Ledigma (Lithuania)
JC Gaudrė (Lithuania)
Rensselaer Polytechnic Institute, Troy NY (USA)
Paul Sabatier University, Toulouse (France)
Sensor Electronic Technology Inc. (USA)

NITRIDE EPITAXIAL TECHNOLOGY AND DEVICE RESEARCH GROUP

10 Saulėtekio, LT-10223 Vilnius
Tel. 236 6069
E-mail:

Head – Dr. Roland Tomašiūnas

STAFF

Chief research fellow: Dr. R. Tomašiūnas.
Senior research fellows: Dr. V. Grivickas, Dr. A. Kadys, Dr. T. Malinauskas.
Research fellows: Dr. V. Bikbajevas, Dr. K. Gulbinas, Dr. T. Grinys.
Junior research fellows: I. Reklaitis, K. Gulbinas, M. Skapas (all part -time).
Doctoral students: I. Reklaitis, M. Skapas, M. Dmukauskas.
Senior engineer: G. Medeišienė (part-time).
Technicians: R. Beresnienė T. Drunga.

RESEARCH INTERESTS

Epitaxy of GaN and alloys, multi-quantum wells by MOCVD technology
Structural, optical and electrical properties of InGaN/GaN multi-quantum wells
Development of GaN devices (LED, detectors, resonators, photonic devices)
Structure and photoluminescence spectroscopy investigation of polar, semi-polar and non-polar III-nitride structures
Trans-cis mobility in polymers, also at the GaN surface
Investigation of photoinduced phenomena and optical memory effect in trinomial chalcogenide layers

RESEARCH PROJECTS CARRIED OUT IN 2016

Projects Supported by University Budget

Development, Investigation and Application of Advanced Semiconductor Structures for Optoelectronics. Dr. R. Tomašiūnas. 2016–2018.

Growth of InGaN/GaN multi quantum well structures emitting light in the green spectra range has been continued by using MOCVD technology. By means of SEM and TEM microscopy, XRD technique the structure of the quantum wells has been investigated and optimized. In the period most of efforts were made to overcome the p-type GaN problem in the growth of “green” InGaN/GaN LEDs structures. Investigation of photo induced phenomena and optical memory effect in trinomial chalcogenide layers has been continued.

National Research Projects

Research Council of Lithuania. Development of Nonpolar GaN on Silicon Growth Technology with Rare-Oxide Interlayers (NEAPOLIS) (No. MIP-15283). Dr. T. Malinauskas. 2015–2017.

The non-polar, semi-polar crystalline GaN growth technology on silicon with rare-oxide interlayer were developed. Monocrystalline semi-polar truncated pyramids and polycrystalline GaN layers with dominating non-polar and semi-polar orientation were grown by MOCVD technique using different growth conditions such as carrier gas, temperature, interlayers. Growth of GaN on different in-plane orientation of (110) ErO was investigated and preferential growth direction was revealed. Grown layers were investigated by XRD, PL and optical transmittance/reflectance techniques.

Main publication:

Grinys, T., Dargis, R., Frentrup, M., Badokas, K., Clark, A., Malinauskas, T. 2016. Facet analysis of truncated pyramid semi-polar GaN grown on Si (100) with rare-earth oxide interlayer. J. Appl. Phys., vol. 120, 105301.

International Research Projects

FP7: Nanostructured Efficient White Leds Based on Short-Period Superlattices and Quantum Dots (NEWLED). Dr. R. Tomašiūnas. 2012–2016.

Fully strained green light emitting InGaN/GaN multiple quantum wells were grown by metalorganic vapor phase epitaxy, using metal precursor multiple flow interruptions during InGaN quantum well growth. The enhancement, as a function of pause duration, appeared to be pulse duration dependent: a lower enhancement was achieved using shorter pulses with optimized relatively shorter pauses. Frequency-domain lifetime measurement technique based on direct harmonic modulation of photoluminescence excitation in the frequency range from 1 Hz to 100 MHz was used to measure charge carrier lifetimes, which spanned from milliseconds to nanoseconds. By this InGaN LED test structures emitting in the blue and green spectral ranges revealed radiative and several nonradiative recombination channels with characteristic nanosecond, submicrosecond, and microsecond decay times. The small-signal frequency-domain lifetime measurement technique was shown being capable to operate in a wide range of LED operating currents. Moreover, being both cheaper and simpler to operate in comparison to the recently suggested SSTRPL technique, it provided recombination coefficients corresponding to the Shockley-Read-Hall, radiative and Auger recombination channels.

Main publications:

Reklaitis, I., Kudžma, R., Miasojedovas, S., Vitta, P., Žukauskas, A., Tomašiūnas, R., Pietzonka, I., Strassburg, M. 2016. Photoluminescence decay dynamics in blue and green InGaN LED structures revealed by the frequency-domain technique. J. Electron. Mater., vol. 45(7), p. 3290.

Dmukauskas, M., Kadys, A,. Malinauskas, T., Grinys, T., Reklaitis, I., Badokas, K., Skapas, M., Tomašiūnas, R., Dobrovolskas, D., Stanionytė, S., Pietzonka, I., Strassburg, M., Lugauer, H.–J. 2016. Influence of metalorganic precursors flow.interruption timing on green InGaN multiple quantum wells. J. Phys. D: Appl. Phys., vol. 49, p. 505101.

M-ERA.NET. Functional Inorganic Layers for Next Generation Optical Devices (FLINGO). Dr. R. Tomašiūnas. 2016–2019.

During the first months of implementation of the project kick-off meeting was visited. Project website was discussed with partners and preparations started. Among partners suitable experimental set-ups need for project implementation were discussed and selected.

MAIN R&D&I (RESEARCH, DEVELOPMENT AND INNOVATION) PARTNERS

Centre for Physical Sciences and Technology (Lithuania)
Kaunas University of Technology (Lithuania)
Translucent Inc. (USA)
OSRAM Opto Semiconductors (Germany)
TOPGAN (Poland)
Royal Institute of Technology (Sweden)
Lawrence Livermore Nacional Laboratory (USA)

OTHER SCIENTIFIC ACTIVITIES

Dr. R. Tomašiūnas –

member of the Doctoral committee Materials Engineering (08T), Vilnius University;
member of the Technical Committee 73 Nanotechnologies, Lithuanian Standards Board;
member of the Lithuanian Material Research Society (LtMRS);
member of the management committee of COST MP1403 Nanoscale Quantum Optics action;
expert of the Latvian Science Council and of the Horizon2020.

Dr. V. Grivickas –

vice president of the Lithuanian Materials Research Society (LtMRS), www.ltmrs.lt/members/v_grivickas/.

Dr. V. Bikbajevas –

member of the Lithuanian Material Research Society (LtMRS);
member of the Lithuanian Physical Society.

ORGANIC OPTOELECTRONICS RESEARCH GROUP

3 Saulėtekio, LT-10257 Vilnius
Tel. 223 4483, fax 223 4482
E-mail:

Head - Prof. Habil. Dr. Saulius Antanas Juršėnas

STAFF

Chief research fellows: Prof. Habil. Dr. S. A. Juršėnas (part-time), Dr. K. Kazlauskas.
Research fellows: Dr. S. Miasojedovas, Dr. A. Miasojedovas, Dr. T. Serevičius, Dr. L. Skardžiūtė (part-time).
Junior research fellows: S. Raišys (part-time), R. Komskis (part-time).
Engineer staff: G. Kreiza (part-time), P. Baronas (part-time), R. Skaisgiris (part-time), J. Jovaišaitė (part-time), Ž. Komičius (part-time).
Doctoral students: S. Raišys, G. Kreiza, P. Baronas, R. Komskis, R. Skaisgiris, J. Jovaišaitė.

RESEARCH INTERESTS

Development of novel organic materials and technologies for optoelectronic applications
Photophysics of organic electronics compounds
Formation of OLED, light upconversion structures and organic sensor systems

RESEARCH PROJECTS CARRIED OUT IN 2016

Projects Supported by University Budget

Organic Optoelectronics. Prof. Habil. Dr. S. A. Juršėnas. 2016–2017.

Efficient synthesis and purification routes of organic electronic compounds were developed. Photophysical properties of functional organic films were optimized for realization of high-performance optoelectronic devices such as OLEDs, sensors etc. Technologies for solution processing of organic materials in inert atmosphere as well as their evaporation in vacuum were acquired. Electron and atomic force microscopies were employed for investigation of surface topography/morphology of organic films. Ultrafast optical pump-probe spectroscopy was applied for evaluation of excited state dynamics in organic electronic compounds.

Main publication:

Raišys, S., Kazlauskas, K., Juršėnas, S., Simon, Y.C. 2016. The role of triplet exciton diffusion in light-upconverting polymer glasses. ACS Appl. Mater. Interfaces, vol. 8, p. 15732–15740.

International Research Projects

Research Council of Lithuania. Joint Lithuania-Japan research project: Towards Organic Laser Transistor (Laser-OTFT) (No. LJB-3/2015). Prof. Habil. Dr. S. A. Juršėnas. 2015–2017.

The project is aimed at developing new organic materials suitable for implementation in organic laser working in a transistor configuration. During the first year, novel bifluorene compounds were designed and extremely low amplified spontaneous emission threshold (700 W cm−2) in the sublimation-grown single crystals of these compounds was demonstrated. Such low threshold was shown to originate from high radiative rates (1.5×109 s−1), absence of excited-state absorption in the gain region, and favourable orientation of transition dipole moments accompanied by excellent wave guiding properties of the single crystals.

Main publication:

Kreiza, G.,Baronas, P., Radiunas, E., Adomėnas, P., Adomėnienė, O., Kazlauskas, K., Ribierre, J.-C., Adachi, C., Juršėnas, S. 2016. Bifluorene single crystals with extremely low-threshold amplified spontaneous emission. Adv. Optical Mater., 1600823.

MAIN R&D&I (RESEARCH, DEVELOPMENT AND INNOVATION) PARTNERS

MBraun Inertgas-Systeme GmbH (Germany)
Centre for Physical Sciences and Technology (Lithuania)
Durham University (United Kingdom)
Centre of Organic Electronics and Photonics Research, Kyushu University (Japan)
Adolphe Merkle Institute, University of Fribourg (Switzerland)
University of Alicante (Spain)
University of Bordeaux (France)
JSC Tikslioji sintezė (Lithuania)
JSC Ledigma (Lithuania)
Kaunas University of Technology (Lithuania)

SEMICONDUCTOR PHOTONICS GROUP

3 Saulėtekio, LT-10257 Vilnius
Tel. 223 4481, fax. 223 4482
E-mail:

Head – Prof. Habil. Dr. Gintautas Tamulaitis

STAFF

Chief research fellows: Prof. Habil. Dr. G. Tamulaitis, Prof. Habil. Dr. E. Kuokštis (all part-time).
Senior research fellows: Dr. R. Aleksiejūnas, Dr. J. Mickevicius (all part-time).
Research fellows: Dr. D. Dobrovolskas, Dr. S. Nargelas, Dr. P. Ščajev, Dr. J. Jurkevičius (all part-time).
Junior research fellows: A. Vaitkevičius, K. Nomeika, Ž. Podlipskas.
Engineer staff: K. Gelžinytė, O. Kravcov.
Technicians: T. Steponavičius, H. Svidras.
Doctoral students: A. Vaitkevičius, O. Kravcov, Ž. Podlipskas, K. Nomeika, K. Gelžinytė.

RESEARCH INTERESTS

Nonequilibrium carrier relaxation, transport and related photoelectrical phenomena in highly excited semiconductors and their nanostructures
Development of laser-based spectroscopic techniques with temporal, spectral, and spatial resolution for characterization of novel semiconductor materials for optoelectronics
Nondestructive characterization of wide band gap semiconductor materials
Optical nonlinearities in semiconductors
Development of ultrafast scintillation detectors and infrared radiation-hard detectors
Development of novel glass ceramic materials for optoelectronic applications

RESEARCH PROJECTS CARRIED OUT IN 2016

Projects Supported by University Budget

Development, Investigations and Applications of Prospective Semiconductors for Optoelectronics. Dr. R. Tomašiūnas. 2016–2018.

The research activities in 2016 were focused on these directions: carrier dynamics and light emission efficiency in III-nitride structures emitting in UV and green spectral regions; light emission properties of III-nitride microrods and multi-stage nanorods; optical properties of novel rare earth doped glass and glass ceramic materials for use as wavelength converters in high power white LEDs.

Main publication:

Podlipskas, Ž., Aleksiejūnas, R., Kadys, A., Mickevičius, J., Jurkevičius, J., Tamulaitis, G., Shur, M.S., Shatalov, M., Yang, J., Gaska, R. 2016. Dependence of radiative and nonradiative recombination on carrier density and Al content in thick AlGaN epilayers. Journal of Physics D: Applied Physics 49, 145110.

National Research Projects

National Research Programme Towards Future Technologies: III-nitride Semiconductors for Radiation-Hard Infrared Detectors (Irdet) (No. LAT-05/2016). Prof. Habil. Dr. G. Tamulaitis. 2016–2018.

The project is aimed at optimization of growth conditions for InN and low-Ga-content InGaN epitaxial layers and heterostructures to meet the requirements for utilization in infrared detectors and to ensure the radiation hardness, which is sufficient for exploitation in space applications.

Research Council of Lithuania. Distinction of the Influences of Defects and Carrier Localization on Emission in Green Ingan LED Structures (Delokingan) (No. MIP-079/2015). Dr. J. Mickevičius. 2015–2018.

In 2016, the studies were focused on technological study of growth of InGaN structures emitting in a wide spectral range using MOCVD and optimization of growth parameters, investigations of spatial distribution of luminescence in InGaN epilayers and quantum well structures, and study of the relation between carrier dynamics and localization in InGaN structures.

European TD COST Action TD1401: Fast Advanced Scintillator Timing (FAST). Prof. Habil. Dr. G. Tamulaitis. 2014–2018.

FAST aims at establishing an interdisciplinary network that brings together experts from different fields of interest in order to develop photon instrumentation with an unparalleled timing precision of < 100ps.

European COST Action MP1302: NanoSpectroscopy. Prof. Habil. Dr. G. Tamulaitis. 2013–2017.

The COST Action NanoSpectroscopy aims at gathering European expertise in order to further develop UV/Vis/NIR/Raman nanospectroscopic techniques and modelling with (ultra-)high spatial, temporal, and spectral resolution and sensitivity, and the application of these techniques to novel (hybrid) (in)organic nanomaterials, complex device structures, and biosystems.

Projects Supported by the Lithuanian Academy of Science

Project: Scintillators for Future Calorimeters (No. CERN-VU-2016-1). Prof. Habil. Dr. G. Tamulaitis. 2016.

Project is devoted to research into new inorganic scintillation materials for novel ionizing radiation detectors for high-energy physics, medical imaging and industrial applications.

Main publications:

Auffray, E., Augulis, R., Borisevich, A., Gulbinas, V., Korjik, M., Tamulaitis G., et al. Luminescence rise time in self-activated PbWO4 and Ce-doped Gd3Al2Ga3O12 scintillation crystals. Journal of Luminescence, vol. 178, p. 54–60, doi: 10.1016/j.jlumin.2016.05.015.

Auffray, E., Korjik, M,. Lucchini, M.T., Nargelas, S., Sidletskiy, O., Tamulaitis, G., et al. 2016. Free carrier absorption in self-activated PbWO4 and Ce-doped Y3(Al0.25Ga0.75)3O12 and Gd3Al2Ga3O12 garnet scintillators. Optical Materials, vol. 58, p. 461–465, doi: 10.1016/j.optmat.2016.06.040.

Korjik, M.V., Auffray, E., Buganov, O., Fedorov, A.A., Emelianchik, I., Griesmayer, E., Mechinsky, V., Nargelas, S., Sidletskiy, O., Tamulaitis, G., Tikhomirov, S.N., Vaitkevičius, A. 2016. Non-linear optical phenomena in detecting materials as a possibility for fast timing in detectors of ionizing radiation. IEEE Transactions on Nuclear Science, vol. 63, iss. 6, p. 2979–2984, doi: 10.1109/TNS.2016.2617461.

INTERNATIONAL SCIENCE PROGRAMMES, PROJECTS AND CONTRACTS

H2020 Project AIDA-2: Advanced European Infrastructures for Detectors at Accelerators. Prof. Habil. Dr. J.V.Vaitkus, Prof. Habil. Dr. G. Tamulaitis. 2015–2018.

VU WP (at Department of New Materials Research and Measurement Technology) Project is devoted to search and investigations of the simple and cheap technology Si wafers for fabrication of dosimeters exploited in dose-reading using VUTEG-5-AIDA instrument.

MAIN R&D&I (RESEARCH, DEVELOPMENT AND INNOVATION) PARTNERS

Centre for Physical Sciences and Technology (Lithuania)
Aixtron AG (Germany)
Rensselaer Polytechnic Institute (Troy NY, USA)
Sensor Electronic Technology Inc. (USA)
Taiwan National University
Crystal Clear Collaboration (RD18) at CERN