Alabama Graphite Finds Natural Graphene in USA

Alabama Graphite is pleased to announce that it has found naturally occurring flake graphene at its Coosa Property in Alabama, USA. The graphene was obtained using an innovative and cost effective process, by Dr. Nitin Chopra of The University of Alabama under our sponsored research partnership.

 

Graphite is made up of multiple layers of graphene stacked on top of each other. Graphene is a single layer of two dimensional (2-D) carbon atoms. Graphene is valued because it exhibits superior electrical, optical, mechanical and thermal properties. It is not only the strongest material known (200 times stronger than steel), but is also one of the most flexible.

“We believe that the discovery of naturally occurring single and multi-layer graphene, on the Coosa Property opens a completely new and unique business dimension for the Company,” stated Ron S. Roda, CEO of Alabama Graphite. “The biggest challenge today for commercial viability of graphene is cost. This presents a very exciting opportunity for our Company.”

“In my opinion, emerging technologies using graphene could greatly benefit from a cost effective processing methodology, with the potential for improved economics and increased production levels relative to any of the current methods used to create synthetic graphene,” commented Dr. Nitin Chopra. “The work done on the Company’s material has the potential to enhance the process of producing scalable, nano-manufactured graphene and graphene-based derivatives.”

Synthetic graphene is currently produced using a variety of expensive, tedious methods that do not lend themselves to large-scale production and are prone to produce defective graphene with uncontrolled flake size. Current synthetic methods for developing graphene include chemical vapor deposition (CVD), mechanical exfoliation, solution exfoliation, and chemo-mechanical methods. This implies higher costs including greater energy consumption, and extended manufacturing time.

The Company and Dr. Chopra continue to jointly develop methodologies to isolate graphene and graphene-based applications. Graphite flakes thinner than 100 nm are of significant interest because of their physical characteristics. Such thin graphite flakes ranging from one 2-D layer of carbon atoms (graphene) or multiple layers of 2-D carbon atoms stacked over each other (multi-layer graphene or graphite nanoplatelets) are of particular interest for developing advanced applications.

As shown in Figure 1 below, a moderately-sized (<5 μm, top right inset) single crystal flake of graphene, from the Coosa Property, is observed with a clearly visible carbon atom arrangement at high resolution (bottom right inset in Figure 1A). These flakes demonstrated very high quality Raman spectral features (G-band intensities, Figure 1B) with the ratio of disordered carbon signature to graphitic carbon signature of around ~0.15±0.05 (ID/IG). In addition, electron transparent flakes (bi-layer and multi-layer graphene) were observed in the analyzed samples.

 

 

Figure 1A) High resolution TEM image of single-layer graphene. Inset (top right) shows low-resolution image of single-layer graphene. Inset (lower right) shows atomic scale TEM image indicating arrangement of carbon atoms (red hexagons) with bond length closely matching that of C-C in graphene network.

 

Figure 1B) Raman spectra for various graphene flakes showing significantly large G-band peak intensity as compared to D and 2D band. This also corresponds to very low I_D/I_G ratio of ~0.15 ± 0.05

 
Rick Keevil, P. Geo., a Director of the Company and VP of Project Development, is a Qualified Person as defined by National Instrument 43-101, has approved the disclosure of the scientific or technical information concerning the Coosa Property contained in this press release.  

A cheap ellipsometer that can be integrated in ALD chambers for in-situ film growth monitoring

A cheap ellipsometer that can be integrated in ALD chambers for in-situ film growth monitoring from Film Sense. Thanks James Greer for posting this one in the ALD LinkedIn Group.

 

Innovative

By sampling discrete bands across the visible spectrum, the Film Sense FS‑1™ Banded Wavelength Ellipsometer realizes many of the benefits of spectroscopic ellipsometry without all the cost and complication.

Powerful

The film thickness and index of refraction of most transparent thin films can be determined with excellent precision and accuracy by a simple 1 second measurement. The multiple wavelength bands of the FS-1 enable the determination of additional sample parameters, such as multiple film thicknesses, surface roughness, and more.

Affordable

The FS‑1 offers the power of Banded Wavelength Ellipsometry™ (BWE), but at the price point of single wavelength ellipsometer and spectroscopic reflectometer systems. The FS‑1 is ideal for measurements in the research lab, classroom, in situ processing environments, industrial control, and more.

FS-1 Banded Wavelength Ellipsometer

FS-1 In Situ Monitoring Capabilities

• Sub-monolayer thickness precision, in real time
• Determine deposition rates and film optical constants n&k, at multiple process conditions, without breaking vacuum
• Monitor and control the deposition of multilayer film structures
• FS-API interface for external software control (LabVIEW™ compatible)
• Applicable to most thin film deposition techniques: Sputtering, ALD, MBE, MOCVD, e‑beam evaporation, etc.

 

Mounting Specifications

• Adapters for mounting the FS-1 light source and detector units to standard 2.75” or 1.33″ conflat vacuum flanges (windows not included)
• Easy to adjust tilt stages for beam alignment
• The FS-1 source and detector units are compact and light (≈1 kg each).
• Can be installed without breaking chamber vacuum

Hybrid copper / graphene nanowires

As published by Phys.org - A new process for coating copper nanowires with graphene has been published by Purdue University - an ultrathin layer of carbon – lowers resistance and heating, suggesting potential applications in computer chips and flexible displays.

Until now it has been difficult to coat copper nanowires with graphene because the process requires chemical vapor deposition at temperatures of about 1,000 degrees Celsius, which degrades copper thin films and small-dimension wires. The researchers have developed a new process that can be performed at about 650 degrees Celsius, preserving the small wires intact, using a procedure called plasma-enhanced chemical vapor deposition (PECVD)

Read more at: http://phys.org/news/2015-03-hybrid-nanowires-eyed-flexible.html#jCp

This illustration depicts a copper nanowire coated with graphene - an ultrathin layer of carbon - which lowers resistance and heating, suggesting potential applications in computer chips and flexible displays. Credit: Purdue University graphic

Chalmers and Thales reduce low-frequency noise in AlInN/GaN HEMTs by ALD/PEALD passivation

As reported by Semiconductor Today, researchers based in Sweden* and France** have been exploring various passivations for reducing low-frequency noise (LFN) in gallium nitride (GaN) high-electron-mobility transistors (HEMTs) with aluminium indium nitride (AlInN) barriers [Thanh NgocThi Do etal, IEEE Electron Device Letters, published online 6 February 2015]. The researchers claim that one of their passivation processes produced the best reported LFN for AlInN/GaNHEMTs.

Effects of surface passivation and deposition methods on the 1/f noise performance of AlInN/AlN/GaN HEMTs

Do, T., Malmros, A. ; Horberg, M. ; Rorsman, N. ; Kuylenstierna, D. ; Gamarra, P. ; Lacam, C. ; Poisson, M. ; Tordjman, M. ; Aubry, R.

Electron Device Letters, IEEE  (Volume:PP ,  Issue: 99 )

This paper reports on effects of Si3N4 and Al2O3 surface passivation as well as different deposition methods on the Low Frequency Noise (LFN) characteristics for AlInN/AlN/GaN High Electron Mobility Transistors (HEMTs). Two samples are passivated with Al2O3, deposited by two different methods: thermal Atomic Layer Deposition (ALD) and plasma-assisted ALD. The third sample is passivated with Si3N4 using Plasma-Enhanced Chemical Vapor Deposition (PECVD). The LFN of the three samples is measured under a bias condition relevant for amplifier and oscillator applications. It is found that the surface passivation has a major impact on the noise level. The best surface passivation, with respect to LFN, is the thermal ALD Al2O3 for which the noise current spectral density measured at 10kHz is 1×10-14 Hz-1 for a bias of Vdd/Idd = 10V/80mA. To the authors’ best knowledge this result sets a standard as the best reported LFN of AlInN/GaN HEMTs. It is also in the same order as good commercial AlGaN/GaN HEMTs reported in literature and thus demonstrates that AlInN/GaN HEMTs, passivated with thermal ALD Al2O3, is a good candidate for millimetre-wave power generation. 

Drain noise current spectra of the three AlInN/AlN/GaN HEMTs versus frequency at 10V, 17mA operating point. (Semiconductor Today, Electron Device Letters, IEEE  (Volume:PP ,  Issue: 99 ) )

* Microwave Electronics Laboratory, Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, , Sweden
** The Wide Band Gap Materials Laboratory and the GaN process Laboratory of 3-5 Lab/Thales Research & Technology, Marcoussi, France

US-Ireland UNITE initiative developing 2D transition metal dichalcogenide materials

Ireland's Tyndall National Institute (based at University College Cork) says it is participating in a three-year US-Ireland collaborative project that aims to reduce power consumption and increase battery life in mobile devices. Under the auspices of the US-Ireland Research and Development Partnership (launched in 2006), researchers will explore new semiconducting materials enabling the further miniaturization of transistors.

 

Researchers in the Republic of Ireland (Tyndall National Institute & Dublin City University), Northern Ireland (Queens University Belfast) and the US (University of Texas at Dallas) - funded by €343,000 from Science Foundation Ireland (SFI), £319,859 from Invest Northern Ireland (InvestNI) and $420,000 from the US National Science Foundation (NSF) government agencies respectively - are collaborating to develop ultra-efficient electronic materials through the UNITE project 'Understanding the Nature of Interfaces in Two-Dimensional Electronic Devices'.

UNITE's principal investigators are professor Robert Wallace at the University of Texas at Dallas, professor Greg Hughes at Dublin City University, Dr David McNeill at Queens University Belfast and Dr Paul Hurley at Tyndall National Institute.

UNITE will create and test the properties of atomically thin, two-dimensional layers of transition metal dichalcogenide (TMD) semiconductors. The properties these materials have displayed to date suggest that they could facilitate extremely efficient power usage and high-performance computing.

"Materials that we are currently reliant on, such as silicon, are soon expected to reach the limit of their performance," says Hurley. "If we want to continue to increase performance, while maintaining or even reducing power consumption, it is important to explore these new TMD materials."

Specifically, UNITE is investigating the synthesis, device fabrication and characterization of 2D TMDs for applications in low-voltage tunnel field-effect transistors. The researchers will explore two separate routes to large-area synthesis through van der Waals epitaxy and atomic layer deposition (ALD). In parallel, characterization and understanding of the surfaces and interfacial regions between commercially available bulk crystals and technologically relevant contacts and insulators will be conducted. This will be accomplished using a combination of in-situ and ex-situ characterization covering questions such as: how can 2D semiconductor surfaces be functionalized to allow uniform and continuous oxide thin films to be formed by ALD; can capacitance-voltage based metrology be applied to metal-oxide-semiconductor systems on 2D semiconductor surfaces; what is the nature of conduction for metal contacts on 2D semiconductors; and how are the atomic-scale electrical properties related to larger-area contacts. The development of growth methods for large-area substrates will not only demonstrate the potential to move 2D semiconductor-based transistors from research to production, but will also provide a source of technologically interesting 2D semiconductor materials for basic study that are not commonly available through geological sources. Finally, the growth and characterization studies will be applied to the fabrication of a tunnel field-effect transistor based on 2D heterostructures.

It is reckoned that, if the UNITE team can understand the issues relating to large-area 2D synthesis, uniform insulator deposition, ohmic contact formation, and charge transport in single- or few-layer 2D semiconductors, then this knowledge will be relevant to a range of potential device architectures.

The application of such 2D TMD materials in transistors could hence not only prolong the battery charge life of portable devices and phones, but also have applications in larger more power-intensive operations such as data storage and server centres. This will have environmental benefits through the reduction of electrical energy consumed by information and communication technologies as well as benefitting consumers.

UNITE builds on the previous US-Ireland collaborative project 'FOCUS' between these academic research partners. The success of this project played a role in demonstrating why funders should back the new project, including training five graduate students in the USA and Ireland, as well as student exchanges between the institutes.

Spatial ALD at low temperature for flexible electronics encapsulation using a BENEQ R2R

A recent paper on Spatial ALD at low temperature for flexible electronics encapsulation using a BENEQ R2R system at Advanced Surface Technology Research Laboratory Team (ASTRaL), Laboratory of Green Chemistry, Lappeenranta University of Technology, Finland. Thanks Henrik Pedersen for finding this one!

Spatial atomic layer deposition: Performance of low temperature H2O and O3 oxidant chemistry for flexible electronics encapsulation

Philipp S. Maydannik, Alexander Plyushch, Mika Sillanpää, and David C. Cameron

Water and oxygen were compared as oxidizing agents for the Al2O3 atomic layer deposition process using spatial atomic layer deposition reactor. The influence of the precursor dose on the deposition rate and refractive index, which was used as a proxy for film density, was measured as a function of residence time, defined as the time which the moving substrate spent within one precursor gas zone. The effect of temperature on the growth characteristics was also measured. The water-based process gave faster deposition rates and higher refractive indices but the ozone process allowed deposition to take place at lower temperatures while still maintaining good film quality. In general, processes based on both oxidation chemistries were able to produce excellent moisture barrier films with water vapor transmission rate levels of 10−4 g/m2 day measured at 38 °C and 90% of relative humidity on polyethylene naphthalate substrates. However, the best result of <5 × 10−5 was obtained at 100 °C process temperature with water as precursor.

Schematic view of modified SALD TFS200R reactor with drum and N2 and precursor inlet, and exhaust ports. J. Vac. Sci. Technol. A 33, 031603 (2015); http://dx.doi.org/10.1116/1.49140

Close up inside the drum of the Beneq TFS 200R, which is  designed for research in Roll-to-Roll atomic layer deposition (ALD) and other forms of continuous ALD (CALD). (www.beneq.com)

Information from BENEQ.com: In the TFS 200R, the flexible substrate is fixed on a rotating cylinder within the reaction chamber. The cylinder itself is surrounded by a number of linear nozzles, each creating an isolated gas region over the full width of the substrate. As the cylinder is rotated, the substrate passes through different gas regions and is coated.

The Beneq TFS 200R, with its robust and modular structure, is designed to meet both industrial standards and the flexibility requirements of research today. Precursor containers are conveniently small, and they can be easily changed. Depending on the process needs, the TFS 200R can be equipped with up to 2 heated sources, type HS 80 and/or HS 180. Additionally, the system can be equipped with up to 8 gas lines and up to 4 liquid sources.

Live from The High-k Workshop at NaMLab in Dresden

Similar to the last years, NaMLab invites to the Novel High-k Application Workshop on March 10th, 2015. New challenges offered by the application of high-k dielectric materials in micro– and nanoelectronics will be discussed by more than 80 participants from industry, research institutes and universities. NaMLab created with the workshop a stimulating European platform for application-oriented scientist to exchange ideas and discuss latest experimental results on MIM-capacitors, process technology, leakage & reliability as well as characterization of high-k dielectrics integrated in silicon based micro– and nanoelectronics.

 

Live from The High-k Workshop at NaMLab Dresden Germany. The Coffee is break sponsored by Oxford Instruments and the event itself by EU COST - Hooking together European research in atomic layer deposition (HERALD)

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