Controlled fabrication of ion track nanowires and channels (original) (raw)

Ion tracks and microstructure technology

International Journal of Radiation Applications and Instrumentation. Part D. Nuclear Tracks and Radiation Measurements

Present-day microtechnology depends very much on the availability of suitable lithographic techniques for generating smaller and smaller structures. On this road, conventional techniques using light particles, such as photons or electrons, are approaching their technological limits. Our goal is to scrutinize the technique of ion track generation in order to extract technologically relevant properties and predict potential fields of future applications. Examples of practical relevance are given.

Heavy Ion track Route to Nanotechnology

Heavy ion tracks recorded in dielectric materials were found to have a width of 5-10 nm using SEM. Heavy ion beams were used for irradiation of Polymers and Muscovite mica to create Ion Track Filters (ITFs) using UNILAC facility at Darmstadt, Germany. The electrochemically etched pores of ITFs used would act as a template. The simple principle of electroplating is used to create heterostructures. The rate of deposition of metallic film depends upon current density, interelectrode distance, cell voltage, electrolyte concentration and temperature etc. The use of ITFs looks quite promising in the fabrication of micro and nanostructures. The morphology of such structures produced through electrochemical methods and replicas of etched tracks in ITFs have been investigated in detail. The efficacy of the technique was tested for growth of quantum dots, fibers, cones, whiskers, micro and nano wires. A 3-dimensional ensemble of Cu-Se was grown electrochemically using ITF of Makrofol-KG. Replication of etched pores in ITFs has been used to develop microtubules. Presently, we are engaged to develop quantum dots, nanorods and nanowires of copper, iron and bismuth using Anodic Alumina Membranes (AAM), Polycarbonate ITFs and Reverse Micelle technique. The preliminary results of our investigations will be presented at NADPA-2008.

Heavy Ion Tracks Route to Nanotechnology

Heavy ion tracks recorded in dielectric materials were found to have a width of 5-10 nm using SEM. Heavy ion beams were used for irradiation of Polymers and Muscovite mica to create Ion Track Filters (ITFs) using UNILAC facility at Darmstadt, Germany. The electrochemically etched pores of ITFs used would act as a template. The simple principle of electroplating is used to create heterostructures. The rate of deposition of metallic film depends upon current density, inter-electrode distance, cell voltage, electrolyte concentration and temperature etc. The use of ITFs looks quite promising in the fabrication of micro and nanostructures. The morphology of such structures produced through electrochemical methods and replicas of etched tracks in ITFs have been investigated in detail. The efficacy of the technique was tested for growth of quantum dots, fibers, cones, whiskers, micro and nano wires. A 3-dimensional ensemble of Cu-Se was grown electrochemically using ITF of Makrofol-KG. Replication of etched pores in ITFs has been used to develop microtubules. Presently, we are engaged to develop quantum dots, nanorods and nanowires of copper, iron and bismuth using Anodic Alumina Membranes (AAM), Polycarbonate ITFs and Reverse Micelle technique. The preliminary results of our investigations will be presented at NADPA-2008.

Characterization of ion tracks in PMMA for single ion lithography

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007

The ultimate resolution in ion beam lithography (IBL) can be achieved by etching tracks modified by the passage of a single ion impact which has a diameter in the order of 10 nm. For precise counting of single ions, a Si photodiode is used as a substrate onto which a PMMA film is spun. We have macroscopically investigated the sensitivity of PMMA using 3 MeV H and found that a deposited energy density of greater than 1 eV/nm 3 is required to remove the PMMA film for 60 s developing in a water:IPA 1:4 solution. From this sensitivity measurement we have determined that 8 MeV F, 71 MeV Cu and 88 MeV I ions should produce enough damage in a single ion strike to create a hole etched along the latent damage track. We have used AFM imaging to quantitatively characterise the hole diameter as a function of the incident ion and the developing time. It was found that for up to 8 min development in a water:IPA solution holes were created for the F, Cu and I ions. SEM imaging has also been used to verify the holes seen by AFM imaging.

Ion track technology – a persisting challenge

New Astronomy Reviews, 1998

A glimpse on the technological potential of ion tracks in solids is provided from research based at the heavy ion accelerator facility in Darmstadt. The high local energy density of swift heavy ions enables micro-and nanostructures previously impossible. Examples are stimulus-responsive ion track membranes, charged capillaries, pinning of magnetic flux lines, and aimed microstructures.

Etched Single-Ion-Track Templates for Single Nanowire Synthesis

The Journal of Physical Chemistry B, 2004

Polycarbonate membranes with one pore only are created by the track-etching technique. Shape and size of the pore are determined by the type of etchant, as well as by the temperature and etching time. The dynamic of single-pore formation during etching is investigated in order to determine the breakthrough time and the track etching rate. The pore is characterized by electrical conductivity measurements and scanning electron microscopy. This kind of template is employed for electrochemical deposition of a single bismuth wire which is left in the polymer for further measurements of its electrical properties.

Multispecies focused ion beam lithography system and its applications

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2013

The authors present a focused ion beam lithography (IBL) instrument and its extension toward using different ion species beyond gallium. The base instrument utilizes a lithography architecture and an ion source and column dedicated to nanofabrication. This includes large area navigation and patterning by a laser interferometer stage, long-term beam to sample positional as well as beam current stability and automation capabilities. Since the ion type can have dramatic consequences on the resulting nanostructures, the authors have extended the gallium IBL tool's ion column and source toward the stable delivery of multiple species for a nanometer scale focused ion beam based on a liquid metal alloy ion source. The IBL system is equipped with an E Â B mass filter capable of selecting different single and multiple charged ion species, simultaneously originating from the same source. The authors investigated different AuSi or AuGe based sources and in particular an ion source delivering Au, Si and Be focused ion beams regarding beam current stability, beam diameter and patterning performance. Depending on the ion species and the interaction with the sample material, the authors achieved sub-20 nm results both for beam diameter and minimum line width by direct milling. The alloy ion sources show stability comparable to gallium during measurements over 10-20 h and a lifetime of several months. Initial and potential applications in the field of selective graphene synthesis, membrane and nanopore patterning as well as photonics and plasmonics are discussed.

Single atom devices by ion implantation

Journal of physics. Condensed matter : an Institute of Physics journal, 2015

To expand the capabilities of semiconductor devices for new functions exploiting the quantum states of single donors or other impurity atoms requires a deterministic fabrication method. Ion implantation is a standard tool of the semiconductor industry and we have developed pathways to deterministic ion implantation to address this challenge. Although ion straggling limits the precision with which atoms can be positioned, for single atom devices it is possible to use post-implantation techniques to locate favourably placed atoms in devices for control and readout. However, large-scale devices will require improved precision. We examine here how the method of ion beam induced charge, already demonstrated for the deterministic ion implantation of 14 keV P donor atoms in silicon, can be used to implant a non-Poisson distribution of ions in silicon. Further, we demonstrate the method can be developed to higher precision by the incorporation of new deterministic ion implantation strategie...

NANOTECHNOLOGY WITH ION TRACK – TAILORED MEDIA

In the first part, we present an overview about a new family of electronic structures that makes use of ion irradiation, to induce electrical anisotropy in one of its components. These structures can, in principle, be scaled down to nanometric dimensions. In the second part, we summarize as an example our recent results on such a structure that contains an organometal.