As opto-electronic technology continues to shrink device sizes, precise information on the structure and composition of low-dimensional systems and nanoscale devices becomes essential. The physical properties of the materials are often determined by atomic-scale features, making advanced characterization techniques crucial. This Core Research Area focuses on understanding the fundamental structure-property relation of nanomaterials through high-sensitivity, high-resolution experimental and modeling tools.
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Semiconductor nanowires are ultra-thin structures with diameters typically smaller than 100 nm and an extremely high aspect ratio. These quasi-one-dimensional materials exhibit unique properties resulting from their nanoscale size, such as enhanced light-matter interaction and carrier confinement. Nanowires can be fabricated using bottom-up approaches like molecular beam epitaxy (MBE), achieving feature sizes down to 10 nm without lithography. Top-down methods offer greater precision, particularly in creating regular nanowire arrays. Regardless of the fabrication approach, nanowires display distinct advantages, including the ability to integrate multiple materials within a single structure, making them ideal for various optoelectronic applications.
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Solid-state systems host various fundamental excitations, such as electrons, holes, excitons, and magnons, which are crucial for future electronic and quantum technologies. In this CReA, we investigate how elastic vibrations, specifically surface acoustic waves (SAWs) and bulk acoustic waves (BAWs), can manipulate elementary excitations at the nanoscale. Using high-quality materials and advanced nanofabrication techniques, we design structures that efficiently couple to dynamic strain fields.
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Quantum-cascade lasers (QCLs) are semiconductor lasers that operate in the terahertz (THz) spectral region, which bridges the gap between microwave and infrared radiation (0.1–10 THz). In this CReA, we focus on the design, molecular beam epitaxy (MBE) growth, fabrication, and optimization of THz QCLs. Our research aims to understand the physical processes in the lasers, enhance their operating temperature, improve wall plug efficiency, and develop compact, cryogenically cooled systems.
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Oxide materials offer a highly versatile platform for the next generation of energy-efficient electronic applications. Their unique physical properties—ranging from superconductivity to magnetism and ferroelectricity—make them promising candidates for novel device concepts.
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The research area of Magnetic Materials for Spintronics and Magnetoacoustics at PDI is in its accelerator phase, building on a strong foundation of expertise in ferromagnet/semiconductor hybrid structures and large-scale 2D van der Waals materials. This field explores new magnetic materials and phenomena for applications in next-generation spintronic and magnetoacoustic devices.
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This CReA explores ultra-wide bandgap nitride semiconductors for next-generation electronic and optoelectronic applications. Using molecular beam epitaxy and advanced spectroscopy, research focuses on high-electron-mobility transistors, novel nitride alloys with unique functionalities, and charge carrier recombination processes. The ZALKAL lab plays a key role in characterizing these materials with time-resolved cathodoluminescence spectroscopy.
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The Nanoelectronics Core Research Area explores quantum effects and transport in artificial hetero- and nanostructures, which we typically fabricate by electron-beam lithography. This CReA is focused on the fundamental electronic dynamics of quantum circuits, which are studied by transport spectroscopy at low temperatures and in high magnetic fields. Their present focus is the interaction between electrons or holes and vibrational eigenstates of the crystal (phonons) as a means of coherent coupling between solid state quantum bits.
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The semiconductor industry has long been dominated by inorganic materials, but organic semiconductors offer new possibilities with their customizable electronic properties, mechanical flexibility, and environmentally friendly nature. These materials enable applications beyond the reach of traditional semiconductors, paving the way for sustainable electronics and spintronics. However, major challenges in organic semiconductor technologies include their inherent disorder and stability, both of which constrain performance and scalability. Addressing these issues requires an interdisciplinary approach that combines advanced fabrication techniques with novel characterization methods.
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