Furthering development in the work of ultra-thin 2D materials which are electrically conductive, flexible and robust, MCN Technology Fellow, Professor Wenlong Cheng and his team have created Plasmene. Similar to Graphene in that it is a free-standing, one particle thick superlattice sheet of nanoparticles, Plasmene differs in that it is entirely artificial and produced via a bottom-up, self-assembly approach.  

This approach utilises silver-coated gold nanospheres which are capped with polystyrene ligands and mixed into a chloroform solution. This is then dropped onto a water droplet on a copper mesh, after which the chloroform evaporates leaving the nanospheres trapped in the grid, forming a lattice-like sheet, which is just nanometres thick but with macroscopic lateral dimensions.

Plasmene’s unique functions separate it from its graphite based cousin, such as visible plasmonics, gap mode plasmonics and propagating plasmonics. Its superior robustness and ability to be folded into geometrically well-defined origami shapes also distinguishes this novel material.

Professor Cheng’s group is experimenting with Plasmene for both sensing devices and nanoelectronics. The nanosheets can be used as a surface adhesive and applied directly to food, money or other common items to detect trace amounts of chemicals from pesticides and drugs which are otherwise difficult to detect.

A particularly interesting outcome of this work is the geometric, origami shapes which have been created using Focused Ion Beam (FIB) Lithography at MCN. ‘Gentle’ FIB milling is used to partially etch the Plasmene sheets by removing the surface-binding polysterene molecules in particular designs. These areas can then be folded by inducing local heating along the milled areas and the angles controlled by programing the milling depth. This gives Professor Cheng and his team sophisticated control over the size, shape and topological features of the origami created. Complex shapes such as cubes, hexagons, hearts, and even the ‘flying bird’ effect have been achieved.

According to Professor Cheng, “this folding ability will be useful for future optoelectronics. As Plasmene is cost effective to make, this could see the development of a range of cheap, new, nanoscale electronic devices. We are also trying to understand how the origami effect can be useful for sensing applications as it is possible for it to affect the sensitivity of the sensors.”

This project was undertaken with the technical expertise of MCN’s FIB specialist, Dr Fatima Eftekhari.

You can read more about this work in the ACS Nano paper, published late last year

ANFF Design House has now grown to incorporate a fourth software suite – IntelliSuite. Covering all aspects of the MEMS design cycle, IntelliSuite provides a groundbreaking, end-to-end software solution for MEMS professionals. Some of the key package elements include:

Blueprint - A layout tool made specifically for the MEMS community, Blueprint supports GDS and DXF layout files and includes a built-in DRC tool. It also allows users to optimise their designs with the Quick3D feature and cross-section viewing capabilities.

• Fastfield Multiphysics - A fully coupled multiphysics tool for electrostatic, mechanical and thermal analysis, Fastfield works directly with IntelliSuite’s MEMaterial database and the Hexpresso meshing engine. Users can also perform unattended, multiphysics-based parametric analyses.
• Cleanroom Process Suite – This suite allows users to either quickly simulate and visualise complex, custom process flows with IntelliFab and FabSim, or select one of the many commercial PDK templates. IntelliEtch enables the rapid simulation of anisotropic etching of silicon or quarts on high-order planes, while the Cleanroom tools use physical solving methods, yielding much more accurate results than traditional voxel-based geometric approximation methods.
• SYNPLE – SYNPLE allows users to capture MEMS designs and systems at a schematic level and optimise by performing rapid behavioral analysis. Fast synthesis of mask layouts and 3D meshed models directly from schematics is also possible.

The IntelliSuite software architecture is based on a unique combination of bottom-up, process-driven design and top-down synthesis. Top-down methodology allows users to quickly explore a wide range of design options, while bottom-up design provides the accuracy to produce first-time right silicon. These methods are combined to get you to your designs faster and with fewer process iterations in the clean room.

IntelliSuite joins Coventor, Tanner EDA and Synopsys in ANFF Design House’s comprehensive suite of software for MEMS, semiconductor processing technologies and devices and 3D visualisation. If you are interested in utilising any of these software suites in support of fabrication projects undertaken at MCN or other ANFF nodes, please contact Design House Coordinator, Shan Don.

Pico Track PCT-150RRE

In a serious advance for wafer processing consistency, throughput and efficiency, MCN has recently installed a Pico Track PCT-150RRE in the class 100 cleanroom to enable automated spin-coating and development of wafers.

A photolithography tool which is used for all process steps before and after exposure, the track system offers users options for both high throughput and single wafer runs while utilising a fully automated and precise robotic system. It is capable of running wafer sizes of 4" and 6" diameter with no change over requirements. Comprised of numerous spin modules, the system can adapt to virtually all photolithography processes with precision and produce patterned wafers with extremely high uniformity. The track system automates all steps continuously including adhesion promoter, pre-baking, resist coating, edge-bead removal (EBR), development, and post-baking.

In addition to the Pico Track, MCN has installed a stand-alone automated developer system for enhanced photolithography processing. Capable of running 2" up to 6" wafer sizes, this new developer system can be used by itself, or in-conjunction with the Pico Track to provide more resist development options for the users of MCN.

MCN anticipates the systems will be available for use in late February 2015.  For any questions around the systems capabilities or availabilities please contact Senior Process Engineer, Bernie Orelup.

ICnanoS2 scanning ion conductance microscope

Co-funded under the MCN and ARC LIEF policy, a scanning ion conductance microscope has recently been installed in the MCN biochemistry lab.

The ICnanoS2 scan head offers a state-of-the-art closed-loop scan system that ensures accurate measurements, low noise levels and sub-nanometer resolution. With an XY scan range of 100μm and a Z scan range of 25μm, it is suited for imaging both living cells and materials. It allows up to 15 mm movement while maintaining sub-nanometer positioning accuracy. The scan head fits a wide variety of modern models of inverted microscopes and integrates with many complementary techniques including confocal microscopy, SECM and electrophysiology.

For more information, please contact Client Services Manager, John Zhu.

Updates to e-Beam evaporator

One of MCN’s key instruments, the Intlvac Nanochrome II Electron Beam and Thermal Evaporation System, has undergone software upgrades that now provide a host of new features and functionalities.

The newly upgraded system now allows for comprehensive automation of nearly all instrument operations. Manual control and process monitoring have been replaced with IntlVac's latest NanoCon software. The new user interface all but eliminates the need for user interaction and should vastly improve rate and thickness control and run-to-run consistency.

Single films or multi-material stacks are easily created using simple layer definitions. Operators can modify ramp and soak parameters, deposition rates, target thicknesses, e-beam settings, and can also make use of ion-beam pre-cleaning and sample heating. Another new feature is the ability to perform ion-beam and heat assisted depositions. Lastly, for those processing on 6" wafers, we have purchased a new 6" planetary dome capable of holding 15 pieces.

For more information or to receive training on the new system, please contact Process Engineer, Yang Lim.

Congratulations to Jegadesan Subbiah et al from Bio21 Institute and CSIRO who recently published “Organic Solar Cells Using a High-Molecular-Weight Benzodithiophene–Benzothiadiazole Copolymer with an Efficiency of 9.4%” in Advanced Materials. The paper discusses a high molecular weight donor–acceptor conjugated polymer being synthesised using the Suzuki polycondensation method. Using this polymer, a single-junction bulk-heterojunction solar cell is fabricated to give a power conversion efficiency of 9.4% using a fullerene-modified ZnO interlayer at the cathode contact. (see figure 1) 

Congratulations to Wenchao Huang et al from Monash University, the Australian Synchrotron and Tianjin University who recently published “Unravelling the Morphology of High Efficiency Polymer Solar Cells Based on the Donor Polymer PBDTTT-EFT” in Advanced Energy Materials. Looking at the microstructure of the polymer PBDTTT-EFT and how it blends with the fullerene derivative PC71BM, the paper investigates achieving solar conversion efficiencies of over 9%. A combination of synchrotron techniques are employed including surface-sensitive near-edge X-ray absorption fine structure spectroscopy and bulk-sensitive grazing-incidence wide angle X-ray scattering. The effect of the solvent additive 1,8-diiodooctane (DIO) on solar cell efficiency and film microstructure is also investigated. (see figure 2) 

Congratulations to Morteza Miansari et al from RMIT University, and Monash University who recently published “Vibration-Induced Deagglomeration and Shear-Induced Alignment of Carbon Nanotubes in Air” in Advanced Functional Materials. The paper discusses Carbon Nanotubes (CNT) which are are widely known to agglomerate into difficult to separate even after suspension in solution. The team report for the first time, a dry and rapid method to deagglomerate bulk, unbound multi-walled carbon nanotube bundles due to surface acoustic waves in a piezoelectric substrate. These nanotubes may then be aligned along the direction of shear provided by sliding a glass cover slip 10 mm across the CNT mat. Uniquely simple, the approach avoids the many shortcomings of other CNT deagglomeration techniques thereby overcoming a key limitation in their use for a diverse range of applications. (see figure 3)