Talk given by Dr. Martin Greve In 2011 the Bergen NanoStructures Laboratory (BNSL) was opened at the Department of Physics and Technology. The laboratory focuses on lithography techniques for manufacturing devices on the nano-scale, mainly by means of electron beam lithography. One of the core research activities in the Nanogroup at UoB is the development of a Neutral Helium Microscope [1]. Focusing a low-energy beam of neutral atoms is routinely done via their Broglie Wavelength using freestanding Fresnel zone-plates fabricated in house using SiNx membranes [2]. The focusing ability of the helium microscope is theoretically limited by the outermost zone width. Due to the mechanical stability, this means a resolution limit in the range of 50 nm. To circumvent this we have recently fabricated and tested the world’s first “atom sieve” based on the photon sieve invented in 2001 [3] [4]. The atom-sieve benefits from a simpler fabrication process, theoretically improved focusing ability and improved signal to noise. The BNSL experience for patterning SiNx membranes initiated a project aiming at fabricating 2D photonic crystals for a new bio-sensor. A novel method for making smaller photonic crystals act as bigger was succesfully proposed and tested [5] [6]. Another research area at BNSL is the investigation of the optical properties of metal nano particles (MNP). Illuminating MNP with white light, will for specific wavelengths give rise to a resonance condition when exciting so-called localized surface plasmons (LSPR). At resonance the MNP will exhibit strong absorption and scattering properties of incident light for these wavelengths. The excited LSPR can decay in several ways, and one of particular interest is through the emission of a so-called hot electron [7]. The optical properties of the nano particles are being investigating, and the aim is to implementing them in a novel metal based solar cell with a tunable absorption spectra, high efficiency and low cost. A method for fabricating large arrays of metal nano particles (MNP) [8] on insulating material such as glass has been established, and is part of an ongoing cooperation on the solar cell project with the local Bergen company EnSol. [1] M. Koch, S. Rehbein, G. Schmahl, T. Reisinger, G. Bracco and W. E. a. B. Holst, "Imaging with neutral atoms – a new matter-wave microscope," Journal of Microscopy, vol. 229, pp. 1-5, 2008. [2] T. Reisinger, S. Eder, M. M. Greve, H. I. Smith and B. Holst, "Free-standing silicon-nitride zoneplates for neutral- helium microscopy," Microelectronic Engineering, vol. 87, no. 043804, pp. 1011-1014, 2010. [3] L. Kipp, M. Skibowski, R. L. Johnson, R. Berndt, R. Adelung, S. Harm and a. R. Seemann, "Sharper images by focusing soft X-rays with photon sieves," Nature, vol. 414, pp. 184-188, 2001. [4] T. Kaltenbacher, S. D. Eder, X. Guo, M. M. Greve, M. Kalläne and L. K. a. B. Holst, "The Atom Sieve: Focussing of a Neutral Helium Beam with a Photon Sieve structure," In preparation, 2014. [5] J. O. Grepstad , M. M. Greve, B. Holst, I.-R. Johansen, O. Solgaard and A. Sudbø, "Finite-size limitations on Quality Factor of guided resonance modes in 2D Photonic Crystals," Optics Express, vol. 21, no. 20, 2013. [6] J. O. Grepstad, M. M. Greve, T. Reisinger and B. Holst, "Nanostructuring of free-standing, dielectric membranes using electron-beam lithography," JVST B, vol. 31, no. 6, 2013. [7] M. W. Knight, . H. Sobhani, J. Nordlander and N. J. Halas, "Photodetection with active optical antennas," Science, vol. 332, no. 5, pp. 702-704, 2011. [8] M. M. Greve, T. O. Håvardstun and B. Holst, "Measuring the localized surface plasmon resonance effect on large arrays (5mm × 5 mm) of gold and aluminum nanoparticles on borosilicate glass substrates, fabricated by electron beam lithography," JVST B, vol. 31, no. 6, 2013.

This event is part of the eventgroup INT Talks

Homepage
https://www.int.kit.edu/events.php

Speaker
Dr. Martin Greve

University of Bergen
Dep. of Physics and Technology, Allégaten 55, 5007 Bergen, Norway

Organizer
Prof. Dr.-Ing. Horst Hahn
Institute of Nanotechnology (INT)
Karlsruhe Institute of Technology (KIT)
Eggenstein-Leopoldshafen
Mail: horst hahn ∂does-not-exist.kit edu

Targetgroup
Interested / Everyone