Postdoctoral Research Positions

Department: Centre of Competence for Terahertz and Hybrid Semiconductor Chips (Vilnius University (VU) or State Research Institute Center for Physical Sciences and Technology (FTMC))

Is the Hosting related to staff position within a Research Infrastructure? No

Contact Information

Organisation / Company Type: Higher Education Institution

Website: https://www.vu.lt/en/

Email: HRaward@vu.lt

Postal Code: LT-01513

Street: Saulėtekio av. 3

Description

Centre of Competence for Terahertz and Hybrid Semiconductor Chips announces a call for five postdoctoral research positions:

Topic 1. Sub-THz integrated circuits for next-generation wireless communications

Employer: VU, Group leader A. Lisauskas

Topic 2. GaN Nanostructures for THz applications

Employer: VU, Group leader A. Žukauskaitė

Topic 3. Modelling and optimisation of THz photomixers for 6G communication

Employer: VU, Group leader P. Ščajev

Topic 4. Structured sub-THz light for 6G communications

Employer: FTMC, Group leader S. Orlov

Topic 5. Hybrid photonic-electronic integration for opto-terahertz conversion

Employer: FTMC, Group leader A. Balčytis

All postdoctoral positions are available at the Centre of Competence for Terahertz and Hybrid Semiconductor Chips established by Vilnius University (VU) in cooperation with the Center for Physical Sciences and Technology (FTMC), Vilnius, Lithuania. Positions are funded from the European Regional Development Fund (ERDF) through the project “Establishment of International Competence Centers,” under which the project No. 10-030-P-0001 "Centre of Competence for Terahertz and Hybrid Semiconductor".

About the research

The primary responsibilities of the postdoctoral researcher will be to conduct high-quality research, present research findings, and prepare scientific publications in the relevant research area. Key duties will also include student supervision, preparing scientific papers, technical reports and test protocols, as well as contributing to intellectual property (IP) documentation, with a target of two patent applications per topic. The researcher will also present findings at international conferences, participate in research visits to partner institutions, including imec and Eindhoven University of Technology, and contribute to the supervision and mentoring of PhD candidates and junior researchers.

Topic 1: Sub-THz integrated circuits for next-generation wireless communications

Develop and experimentally validate semiconductor components and integrated circuits for sub-THz wireless communication in the 140–325 GHz range. The research will focus on RF CMOS, SiGe BiCMOS and GaAs technologies and explore methods of development and integration of components fabricated using complementary technologies into sub-THz electronic systems.

1. Design and optimise sub-THz integrated circuits, including detectors, receiver front ends, mixers and frequency-conversion circuits, using circuit and electromagnetic modelling tools.
2. Prepare circuit layouts and test structures for multi-project wafer fabrication in selected RF CMOS, SiGe BiCMOS or GaAs technologies. Perform physical verification and use experimental results to validate and refine device and circuit models.
3. Investigate interposer-based interconnects, chip-to-antenna interfaces and packaging solutions in collaboration with other teams operating in the Centre.
4. Contribute to the integration and experimental evaluation of the developed components in a laboratory sub-THz communication platform.

Topic 2: GaN Nanostructures for THz applications

Design, grow, and optimize GaN nanostructures (nanowires, nanodots, "dot-in-wire" configurations, and nanostructure arrays) using MOCVD to enhance terahertz wave generation, field amplification, and detector sensitivity in the sub-THz range (140–325 GHz).

1. Growth and optimization of GaN nanostructures by MOCVD with controlled diameter, length, density, and arrangement. Structural, optical, and electronic characterization (XRD, AFM, SEM/TEM, optical/electrical THz testing) of grown nanostructures
2. Investigation of dimensionality and confinement effects on THz response in collaboration with theoretical modeling and device engineering teams, supplying measured material parameters to the modeling group for model validation and iterative growth optimization.
3. Coordination of joint work on integration of optimized heterostructures and nanostructure arrays into THz emitters and detectors in collaboration project parters.

Topic 3: Modelling and optimisation of THz photomixers for 6G communication

Develop and validate THz photomixer/detector structures through numerical modelling. The aim is to develop >10 Gbit fiber-optic internet interconnect to THz channel (140–320 GHz).

1. Construct and model THz photomixer devices using different materials (GaAsBi, InGaAs, InGaAsBi, InAs/AlInAs, GeSnSi, CdSeTe, InGaN, GeSiC, SnAlGaN, perovskites) and heterostructures (MQW) for modulated THz emission at submiliwatt powers.
2. Construct and model THz detector devices (high electron mobility transistors) for modulated THz signal detection (eg. AlGaN/GaN THz HEMT).
3. Investigate fiber-optic internet prototype interconnect to THz channel to compensate phase noise and enhance bitrate. Model circuits for detecting amplitude and phase modulation.
4. Model phase and amplitude noise for signal transmission through various obstacles.

Topic 4: Structured sub-THz light for 6G communications

Develop and experimentally validate new methods for generating and controlling structured sub-THz beams (OAM, Bessel and Airy) using meta-antennas and metasurfaces. The aim is to build a unified channel model and demonstrate a laboratory sub-THz link (140–320 GHz, >100 m)

1. Build a unified sub-THz channel model for non-paraxial and phase-structured beams (OAM, Bessel, Airy) with the modelling team. This includes electromagnetic simulations and validation against experimental data.
2. Design meta-antennas and active metasurfaces (CST/HFSS), and support prototype fabrication by femtosecond laser ablation and their THz characterization (beam profiles, phase and amplitude mapping, efficiency, losses).
3. Contribute to the chip-to-free-space interface and the integration of photonic components, including loss-reduction strategies.
4. Take part in building and testing the laboratory communication channel (data transmission, robustness to obstacles and disturbances, system optimization).

Topic 5: Hybrid photonic-electronic integration for opto-terahertz conversion

Develop and experimentally validate heterogeneous integration methods that combine CMOS-compatible silicon nitride photonic integrated circuits with active materials (thin-film lithium niobate, InGaAsBi photoconductors) and high-frequency electronic components (amplifiers, antennas, THz detectors). The goal is efficient conversion between continuous wave telecom C-band optical signals and sub-THz (100–300 GHz) waves for next-generation wireless communication links.

1. Design and assess heterogeneous integration schemes linking photonic chips with photoconductive and electro-optic layers and with sub-THz electronic components developed within the Centre. This includes chip-to-chip interconnects, transitions, bonding and packaging approaches, such as micro-transfer printing, flip-chip and wire bonding.
2. Analyse technological compatibility between photonic platforms (SiN, Si, LNOI) and semiconductor technologies (RF CMOS, SiGe BiCMOS, GaAs, InGaAsBi). From this analysis, derive material and component models, design rules and technology parameter specifications. Participate in preparing GDS layouts for multi-project wafer runs (imec, CORNERSTONE).
3. Experimentally validate the integrated optical-to-sub-THz interface at system level, including characterisation of the individual photonic and electronic components, their interconnects and the complete link, and demonstration of high-speed data transmission over a sub-THz carrier.
4. Coordinate joint work between the Centre’s photonics, semiconductor and high-frequency electronics teams, collaborate with international partners (imec, TU/e, RMIT University).

Position Details

• Duration: up to 24 months (2 years) full-time (40 h/week) fixed-term employment contract.
• Location: NFTMC building, Sauletekis av. 3, Vilnius, Lithuania
• Salary: 35.600 EUR/year (incl. taxes).
• Resources: Access to the research infrastructure of VU and FTMC (cleanrooms, THz and photonics laboratories, epitaxy and device-processing facilities) and funding for conferences and research visits to partner institutions.
• Expected start: January - September 2027 (exact dates will be agreed upon with specific topic leaders).

Requirements for Candidates

• PhD in physics, electrical engineering, materials science, photonics, nanotechnology or related discipline obtained within the last 5 years (before the start of the postdoctoral position).
• The dissertation must have been defended in a different institution than the one the candidate applies to.
• Proficiency in English (C1 level and above).

Specific requirements depending on the topic:

• Topic 1:
  • Research experience in RF, mm-wave or sub-THz integrated circuit design in at least one relevant semiconductor technology, such as RF CMOS, SiGe BiCMOS or GaAs, and a sound understanding of semiconductor devices and high-frequency circuit operation.
  • Practical experience with circuit simulation and IC layout tools, such as Keysight ADS or Cadence, and familiarity with electromagnetic modelling using tools such as CST Studio Suite or HFSS.
  • Experience with IC fabrication runs, experimental RF/mm-wave/THz characterisation, noise measurements, heterogeneous integration, high-frequency packaging or communication-link testing would be an advantage.
• Topic 2:
  • Experience with MOCVD growth process and typical thin film or nanostructure characterization techniques.
  • Knowledge of III-nitrides material system, growth of nanostructures, fabrication and operational principles of HEMTs, and experience in THz physics and technology would be an advantage.
• Topic 3:
  • Knowledge of semiconductor photonics and RF (carrier and photon transport, semiconductor material optoelectronics, RF electronics, quantum devices, antennas etc.).
  • Knowledge on modelling of optoelectronic devices at least with COMSOL multiphysics (at least Semiconductor Module, RF Module, Wave Optics Module, Direct Monte Carlo Simulation), data analysis and consolidation.
• Topic 4:
  • Knowledge of photonics and RF integration, experience in THz or mmWave physics and technology, structured light (OAM, Bessel, Airy beams), or metasurfaces and antennas.
  • Hands-on experimental skills, such as THz continuous-wave systems, beam profiling, electrical lock-in detection, VNA and probe-station measurements. Experience with wireless channels or communication-link characterization (BER, SNR).
• Topic 5:
  • Experience with heterogeneous or hybrid integration, chip packaging, or cleanroom microfabrication (lithography, metallisation, etching).
  • Experience in design and modelling of high-frequency structures, such as CST or HFSS, at RF, mm-wave or THz frequencies.
  • Experience with photonic chip characterisation (fibre coupling, optical spectrum analysis) and/or RF/mm-wave measurements (VNA, S-parameters).

How to Apply

Application should be sent via email: THzhybridchips@ff.vu.lt and must include:

1. Narrative Curriculum Vitae (CV).
2. List of the most important scientific publications.
3. Copy of PhD certificate.
4. Motivation letter (stating the topic of interest).

About the Centre

The international Centre of Competence for Terahertz and Hybrid Semiconductor Chips newly established at Vilnius University and Center for Physical Sciences and Technology opens five postdoctoral researcher positions and invites to apply ambitious and motivated researchers. The Centre brings together the knowledge, expertise, competencies and technological facilities of VU, FTMC in semiconductors, terahertz (THz) physics, optoelectronics and photonics, together with the project partners Eindhoven University of Technology (TU/e, the Netherlands) and imec (Leuven, Belgium).

Participating institutions

Vilnius University (VU, Vilnius, Lithuania)

With nearly of 450 years of academic history (established in 1579), Vilnius University (Vilnius University) is the oldest and the most comprehensive university in Lithuania ranked as the nation’s leading institution in research and high education. Today VU integrates deep academic traditions, wide scale of research together with a forward-looking vision via 15 faculties and scientific centres covering large variety of fields — from humanities and social sciences to physics, medicine, and life sciences.

Faculty of Physics is the largest and one of the most attractive places to study physics and make research in physics in Lithuania. The Departments unites efforts of internationally recognized scientific groups in the field of laser physics for their breakthrough discoveries and exploration in parametric gain effects and innovative developments in tunable laser systems. A particular role is dedicated to investigation of different semiconductor materials and compounds employing dynamical grating approach, using ultrafast spectroscopy techniques. The Department is famous in the field of investigation of organic materials and their-based light emitting diodes; the faculty staff coordinates Lithuania's collaboration with CERN through the Experimental Nuclear and Particle Physics Center. – In the current project, the efforts of the faculty teams will be dedicated for the development of CMOS- and BiCMOS -based semiconductor chips for THz frequencies, their systematic investigation and applications for 6G wireless communication systems. Special attention will be given for GaN structures growth by MOCVD technology and their comprehensive investigation, GaN-based structures application for THz devices like modulators, phase shifters and waveguides.

Center for Physical Sciences and Technology (FTMC, Vilnius, Lithuania)

The Center for Physical Sciences and Technology (FTMC, https://ftmc.lt/en/) is the largest non-university scientific organization in the Baltic states with more than 700 staff including more than 500 researchers. The FTMC is RTO organization, member of EARTO. The Center is focused on advancing science-based innovations and contributing to technological progress that benefit industry, society and national interests.

The activities will be focused in two Departments. The Department of Optoelectronics has established a THz technology cluster covering the entire value chain — from semiconductor materials by design, their growth using molecular beam epitaxy up to device design, fabrication, investigations and possible applications. The team have successfully developed novel GaAsBi-compounds, applied them for compact THz time-domain spectroscopic systems. Novel room temperature THz sensors (bow-tie diodes, bolometers, etc) were produced; compact homodyne, heterodyne and spectroscopic THz imaging systems were developed, innovative solution in diffractive optics and metamaterials for flat THz optics were suggested. Applications of THz structured light for imaging were studied establishing design rules for non-paraxial THz imaging systems. The Department of Physical Technologies specializes in semiconductor device processing and fabrication, focusing on GaN-based structures for THz modulation, significantly improving amplitude modulation and phase shifts near 2D plasmon resonance, and developing electro-optical THz modulators.

Eindhoven University of Technology (TU/e, the Netherlands)

TU/e (https://www.tue.nl/en/) is one of the leading technological universities in the Netherlands, renowned for its expertise in electrical engineering, electronics, and applied research. Collaboration with its Department of Electrical Engineering will focus on research in electronics and engineering, contributing to the development of terahertz technologies and hybrid chip solutions.

Interuniversity Microelectronics Centre (imec, Leuven, Belgium)

Imec (https://www.imec-int.com/en) is a world-leading research and innovation centre in nanoelectronics and digital technologies, with advanced infrastructure for semiconductor development, silicon photonics, radio-frequency technologies, and 3D integration. Joint research will focus on next-generation chips and advanced heterogeneous integration solutions relevant to terahertz technologies a