Antennas & Waves

In a wireless system, the antenna is the interface between the electric circuit and waves propagating in the surrounding medium. From a system point of view, the antenna operates under several fundamental constraints in terms of available bandwidth, gain etc versus, for instance, the available volume or complexity in the matching network. Waves propagating and interacting with a complex surrounding are challenging to model, requiring extensive simulations, measurements, and thorough mathematical analysis.

• Lundgren, J., Helander, J, Gustafsson, M., Sjöberg, D, Xu, B., Colombi, D.: A Near-Field Measurement and Calibration Technique: Radio-Frequency Electromagnetic Field Exposure Assessment of Millimeter-Wave 5G Devices, IEEE Antennas and Propagation Magazine 63 (3), 77-88, 2021.
• Jelinek, L., Gustafsson, M., Capek, M., Schab, K.: Fundamental bounds on the performance of monochromatic passive cloaks, Optics Express 29 (15), 24068-24082, 2021.

Metamaterials

Metamaterials combine different materials with variations on a mesoscopic/microscopic scale, which enables exceptional performance on a macroscopic scale when properly designed. We study the fundamental bounds of these classes of materials, as well as their efficient design and application areas, such as functional materials with frequency and polarization selective properties. This entails both the development of advanced simulation models and manufacturing and experimental verification.

• Lundgren, J., Gustafsson, M., Sjöberg, D. and Nilsson, M. IR and metasurface based mm-wave camera. Applied Physics Letters, 118(18), p.184104. (2021)
• Ericsson, A., Sjöberg, D., Gerini, G., Cappellin, C., Jensen, F., Balling, P., Fonseca, N.J. and de Maagt, P.. A Contoured-Beam Reflector Satellite Antenna Using Two Doubly Curved Circular Polarization Selective Surfaces. IEEE Transactions on Antennas and Propagation, 69(2), pp.658-671. (2020)

Nanoelectronics for IoT

Internet-of-things (IoT) requires a large number of units, which contain sensors and computing devices,that can exchange data with other devices and systems through wireless connections, over the internet or through other communication networks. Since most of the units are battery powered, electronic devices and circuits witha low power consumption are required. We develop novel tunnel field effect transistors, using heterostructure III-V nanowires, that rely on quantum mechanical tunneling as an energy filter for electrons. This enables very low power operation due to the steep switching slopes, which is ideal for low power circuits and sensors.

• E Memisevic, J Svensson, M Hellenbrand, E Lind, LE Wernersson. Electron Devices Meeting (IEDM), 2016 IEEE International, 19.1. 1-19.1. 4, (2016)
• Krishnaraja, A., Svensson, J., Memisevic, E., Zhu, Z., Persson, A. R., Lind, E., Wallenberg, L. R. & Wernersson, L. E., ACS Applied Electronic Materials. 2, 9, p. 2882-2887 6 p (2020)

Neuromorphic Computing

Artificial intelligence and Deep learning have emerged as tools for a smart and digitalized society. For these data-heavy applications, the traditional von Neumann computing hardware architecture cannot keep up and new hardware architectures are needed. Neuromorphic computing systems embrace the parallelism and connectivity of the biological brain appliedto electronic hardware, making use of nanoscale memristive devices to achieve artificial synaptic and neuronal functionality. We explore ferroelectric and redox-reaction resistive memristors in combination with III-V semiconductors to realize energy-efficient neuromorphic systems.

• Athle, R., Persson, A.E.O., Troian, A., Borg, M., “Top Electrode Engineering for Freedom in Design and Implementation of Ferroelectric Tunnel Junctions based on Hf1-xZrxO2", ACS Applied Electronic Materials, 4, 3, 1002–1009 (2022)
• Mamidala, S.R., Persson, K.-M., Irish, A., Jönsson, A., Timm, R., Wernersson, L.-E., “High-density logic-in-memory devices using vertical indium arsenide nanowires on silicon”, Nature Electronics 4, 914-920 (2021)

Quantum Technology

Pure quantum mechanical effects such as entanglement, superpositions and superconductivity can all be used to build electronic devices and systems with performance which goes beyond that of which is possible for classical electronic devices. The quantum effects tend to be delicate and requires device operation at very low temperatures, We study, build and evaluate superconductor/semiconductor devices for quantum computing as well as traditional amplifier circuits. We also investigate the behavior of traditional electronic devices operating at cryogenic temperatures.

• Södergren, L., P. Olausson, and E. Lind. "Cryogenic Characteristics of InGaAs MOSFET." IEEE Transactions on Electron Devices 70.3 (2023): 1226-1230.
• Olausson, L., Olausson, P., & Lind, E. (2024). Gate-controlled near-surface Josephson junctions. Applied Physics Letters, 124(4).

THz & Power Electronics

High frequency electronics and efficient power electronics are important for a variety of everyday applications such as signal transmission for wideband communications, compact radar systems and the electrical grid. We are investigating how (ultra) wide bandgap materials can be implemented to construct highly efficient and scaled switches for operation with device breakdowns above 1.2kV. A special interest is in novel material and device geometries. On the other end of the spectrum, we investigate small bandgap materials for implementation of (ultra) low noise devices in high frequency systems targeting technology development and circuit design.

• S. Andrić, L. O. Fhager and L. -E. Wernersson, "Millimeter-Wave Vertical III-V Nanowire MOSFET Device-to-Circuit Co-Design," in IEEE Transactions on Nanotechnology, vol. 20, pp. 434-440, doi: 10.1109/TNANO.2021.3080621 (2021)
• Gribisch, Philipp, et al. "Capacitance and Mobility Evaluation for Normally-Off Fully-Vertical GaN FinFETs." IEEE Transactions on Electron Devices (2023).