Controlled fabrication of advanced nanostructures

The research in all areas within NanoLund requires access to designed nanostructures. Our key expertise is in solid-phase nanostructures fabricated from the vapour phase, especially metal nanoparticles, atomically thin oxide films, and semiconductor nanowires. We fabricate nanostructures using bottom-up and top-down approaches, or by a combination of both. To ensure high-quality nanomaterials, experiment is combined with theory and simulations to warrant a fundamental understanding of the material formation process.

Project areas:

Engineered nanoparticle synthesis

Smart nanomaterials with designed properties based on nanoparticles have the potential to revolutionize applications in different areas ranging from magnetics to catalysis and optoelectronics. We use aerosol-based methods to create monodisperse metal, metal oxide, semiconductor and alloy nanoparticles with the aim to fully understand and control the formation process to produce nanoparticles with tailored size, shape and composition to meet the demands for intended

applications. Modeling and theory are combined with experiments to optimize both nanoparticle formation and deposition. The application areas within NanoLund for our engineered nanoparticles include catalysis research, nanowire growth and research on nano safety.

Design of novel advanced semiconductor nanowires

Fabrication of high quality III–V semiconductor nanowires primarily using chemical beam epitaxy or metal-organic vapor phase epitaxy has been a key research area within NanoLund since before year 2000. More than 20 years’ experience and focus is resulting in high quality nanowire structures of virtually all III-V element combinations, atomically sharp heterostructures with sharp interfaces and accurate composition control. Control of both crystal structure and

chemical composition gives unique possibilities to achieve new electronic devices, solar cell material, thermoelectric and quantum physics devices and gives the possibility to measure electronic properties of structures with single defects incorporated. There is a strong link to experiments that can be visualised in the Environmental TEM.

Understanding nanowire growth

We explore the growth mechanisms of semiconductor nanowires. Knowledge about how nanowires grow is not only important from a fundamental materials science perspective, but is also crucial for controlled and reproducible fabrication of nanowires. We always correlate the theoretical understanding that we are developing with the empirical knowledge gained from the experiments, including nanowire growth experiments inside an environmental TEM. We use mass transport modeling, in order to understand the axial growth rate as a function of growth conditions and to understand the extent of interface grading in axial heterostructures. In addition, we use nucleation modeling in order to understand the formation of various polytypes (crystal modifications that differ in stacking sequence only) in nanowires.

Being able to precisely tune the heterostructure properties (composition control) and the polytypes (crystal structure control) gives additional degrees of freedom when designing devices where III–V semiconductor nanowires are the vital parts. For this we use two-component nucleation modeling with thermodynamically assessed chemical potentials.

Key publications

Hydrogen assisted spark discharge generated metal nanoparticles to prevent oxide formation. R. T. Hallberg, L. Ludvigsson, C. Preger, B. O. Meuller, K. A. Dick and M. E. Messing: Aer. Sci. Technol. 52, 347-358 (2018). DOI: 10.1080/02786826.2017.1411580
See Article Hydrogen assisted spark discharge at Publisher's Site

Nucleation-limited composition of ternary III–V nanowires forming from quaternary gold based liquid alloys. Egor D. Leshchenko, Masoomeh Ghasemi, Vladimir G. Dubrovskiic and Jonas Johansson: CrystEngComm, 2018, 20,1649. DOI: 10.1039/C7CE02201H
See Article Nucleation-limited composition at Publisher's Site

Interface dynamics and crystal phase switching in GaAs nanowires Daniel Jacobsson, Federico Panciera, Jerry Tersoff, Mark C. Reuter, Sebastian Lehmann, Stephan Hofmann, Kimberly A. Dick & Frances M. Ross. Nature 531, (2016) 317-322. DOI: 10.1038/nature17148
See Article Interface dynamics at Publisher's Site

Key faculty

Recent theses

Linus Ludvigsson, Physical Characterization of Engineered Aerosol Particles, PhD thesis, Lund University 2017.
See Linus Ludvigsson's thesis at the Research Portal

Gaute Otnes, III-V Nanowire Solar Cells: Growth and Characterization, PhD thesis, Lund University 2018.
See Gaute Otnes' thesis at the Research Portal

Luna Namazi, From Understanding to Realizing Novel III-Sb Materials via Nanowires, PhD thesis, Lund University 2018.
See Luna Namazi's thesis at the Research Portal

Xulu Zeng, InP/GaInP Nanowires for Tandem Junction Solar Cells: Growth, processing and characterization, PhD thesis, Lund University 2018.
See Xulu Zeng's thesis at the Research Portal

Rong Sun,Understanding the Role of Seed Particle Material on III-As Nanowire Growth, PhD thesis, Lund University 2018.
See Rong Sun's thesis at the Research Portal

Vilgaile Dagyte, Growth and Optical Properties of III-V Semiconductor Nanowires - Studies Relevant for Solar Cells, PhD thesis, Lund University 2018.
See Vilgaile Dagyte's thesis at the Research Portal

Robert Hallberg, Aerosol Metal Nanoparticles and their Role in Particle-Assisted Growth of III–V Nanowires, PhD thesis, Lund University 2018.
See Robert Hallberg's thesis at the Research Portal