Developing new processes and applications

There is a continuous challenge to develop new processes, whether it is due to changing a material in a known process, completely new materials or upscaling to industrially viable processes. With the bottom-up approach utilized in NanoLund, the nanostructures can be designed for a particular device or application.

Project areas:

Nitride materials

The nitride semiconductors (InN, GaN, AlN) are different from the ordinary III/V compounds in that the thermodynamic bulk structure of all of them is hexagonal, as compared to the other cubic III-V semiconductors. They also demand higher growth temperatures, and can readily be grown without seed particles. However, the band gap of these materials are in general larger, giving

Cover of a book
light emission in the UV-Blue region. There is promise of having very efficient LED:s based on these materials, ranging over the whole visible region by combinations of different nitrides, but to achieve this, the problem of avoiding threading dislocations due to the lattice mismatch at the interfaces have to be resolved.
Selected area growth, where small perfect nuclei can be grown from small holes in a mask, is one way of generating perfect single crystals, and by combinations of kinetic and thermodynamic growth, specific facets can be enhanced to show pyramidal, wire-like or prismatic nanostructures, giving varying application areas.

Aerotaxy: large-scale, gas-phase nanowire synthesis

Aerotaxy is a new method for growing semiconductor nanowires without involving a substrate, which we are trying to develop into a scalable process for mass production of designed nanowire materials. In short, Aerotaxy works by creating an aerosol of catalytic

aerotaxy image
seed particles and adding precursor molecules in a tube furnace, which causes nanowires to grow at a very high speed of more then 1 µm/s, which is 100 – 1000 times faster than the substrate-based methods. The nanowires can be collected in filters, directly on substrates or dispersed in liquids. The nanowires are being studied using scanning and transmission electron microscopy, photoluminescence, scanning tunnelling microscopy, and with electrical transport.
The origin of the technology is due to a unique combination of aerosol and nanowire science, and builds on early work on aerosol synthesis of semiconductor nanoparticles. The fundamental motivation for the research is to reach a better understanding of the intrinsic mechanisms of nanowire growth, without a substrate being involved. The practical motivation is that nanowires show great potential for applications in solar cells, light emitting diodes, batteries or nanoelectronics.

Key publications

Continuous gas-phase synthesis of nanowires with tunable properties.M. Heurlin, M. H. Magnusson, D. Lindgren, M. Ek, L. R. Wallenberg, K. Deppert, and L. Samuelson, Nature, 2012, 492: 90. DOI: 10.1038/nature11652
See article continuous gas phase synthesis at publisher's site

High In-content InGaN nano-pyramids: tuning crystal homogeneity by optimized nucleation of GaN seeds. Zhaoxia Bi, Anders Gustafsson, Filip Lenrick, David Lindgren, Olof Hultin, L. Reine Wallenberg, B. Jonas Ohlsson, Bo Monemar and Lars Samuelson. J. of Applied Physics 123 (2), (2018) 025102. DOI: 10.1063/1.5010237
See article high In-content nanopyramids at publisher's site

GaAsP Nanowires Grown by Aerotaxy. Metaferia, Wondwosen; Persson, Axel R.; Mergenthaler, Kilian; Yang, Fangfang; Zhang, Wei; Yartsev, Arkady; Wallenberg, Reine; Pistol, Mats-Erik; Deppert, Knut; Samuelson, Lars; Magnusson, Martin H. NANO Letters 16:9 ( 2016) 5701-5707. DOI: 10.1021/acs.nanolett.6b02367
See article nanowires grown by aerotaxy at publisher's site

Key faculty