Thursday, December 20, 2007

Atomic Layer Deposition Replicates Fly's Eye, Demonstrates Novel Optical Properties

Dr. Zhong Lin Wang, Regents' Professor, COE Distinguished Professor, and Director, Center for Nanostructure Characterization, at Georgia Tech, has examined the fine structure of the compound eyes of a household fly and precisely replicated its entire structure using a low-temperature atomic layer deposition technique. The results have been published in the December 6, 2007 online edition of Nanotechnology ("Bio-inspired fabrication of antireflection nanostructures by replicating fly eyes").
"Our contribution is the ability to replicate a biological structure and then measure its physical properties and find out why a particular structure exhibits unusual properties" Wang explains to Nanowerk. "By doing so, we are trying to find an effective fabrication path that follows the evolution of Nature for making extraordinary nanostructures."
"The surface of the fly eye is covered by highly packed protuberances, which potentially increases visual efficiency through increased photon capture for a given stimulus" Wang comments on his group's most recent bioinspired nano research. "We carefully examined the fine structure of the household fly compound eye and then completely replicated the entire configuration by alumina through a low-temperature atomic layer deposition process."

Insects have compound eyes – instead of one lens they see through a sphere with many hundreds or thousands of eyes, so called ommatidiums. Household flies, for instance, have a very well-developed visual system with the capacity of seeing motion, color and pattern of objects in their environment due to their advanced compound eyes.
The Georgia Tech scientists' goal has been focused on the optical properties of the fly eye's nanostructure, aiming to understand the visible light, UV light and infrared light transmission through the structures.
"We achieved the alumina replica by removing the fly compound eye template at high temperature, and the alumina coating was crystallized simultaneously" Wang describes the experimental details. "The success of our replication was not only with the morphologies but also with the optical features – the unique antireflection property of the eye was also inherited by the alumina replica. By measuring the reflective spectra of the replica, we demonstrated that the alumina replica of a fly eye was an efficient antireflection structure of visible light at an incident angle up to 80°."
Wang says that the fly eye replica with antireflection structure exhibits great potential in the applications of optical coating, sensing or lens arrays. His group is now working on developing more sophisticated replication techniques for tuning the optical response of the structure in order to optimize the performance.

Monday, December 17, 2007

NIST imaging system maps nanomechanical properties

The National Institute of Standards and Technology (NIST) has developed an imaging system that quickly maps the mechanical properties of materials—how stiff or stretchy they are, for example—at scales on the order of billionths of a meter. The new tool can be a cost-effective way to design and characterize mixed nanoscale materials such as composites or thin-film structures.
The NIST nanomechanical mapper uses custom software and electronics to process data acquired by a conventional atomic force microscope (AFM), transforming the microscope’s normal topographical maps of surfaces into precise two-dimensional representations of mechanical properties near the surface. The images enable scientists to see variations in elasticity, adhesion or friction, which may vary in different materials even after they are mixed together. The NIST system can make an image in minutes whereas competing systems might take an entire day.

IMAGE: An atomic force microscope normally reveals the topography of a composite material (l.) NIST's new apparatus adds software and electronics to map nanomechanical properties (r.) The NIST system reveals that the glass fibers are stiffer than the surrounding polymer matrix but sometimes soften at their cores.

Physical Vapor Deposition to Generate $10 Billion in 2008

World physical vapor deposition industry will be worth an estimated $9 bln in 2007 and $9.9 bln in 2008. It should reach $16.7 bln by 2013, a compound annual growth rate (CAGR) of 11% over the 5-year period, BCC Research says. The market is broken down into applications of PVD equipment, materials deposited and services. Of these segments, the PVD equipment will remain the largest market as shipments grow at CAGR of 9.6% to reach an estimated $7.1 bln in 2008 and then increase to $11.9 bln in 2013, at a CAGR of 10.9%. Materials deposited hold the second largest share of the market. Worth an estimated $1.3 bln in 2007, this segment is expected to be worth $1.5 bln in 2008 and $2.7 bln in 2013, a CAGR of 12.4% over the forecast period. The value of services will increase from $1.2 bln in 2007 to $1.3 bln in 2008, and will increase at a CAGR of 9.9% to reach $2.0 bln by 2013.

Thursday, December 13, 2007

Thin Films CIGS Solar Cell at ETH Zurich

Rubens Tube: Fascinating Physics (Not Strictly Thin Films but Just for Fun)

Thin-Film Battery Attains Commercial Availability

Cymbet has announced commercial availability of its EnerChip thin-film battery products, the first commercial solid-state, highly rechargeable thin-film battery technology for the semiconductor industry. The solid-state battery can be integrated as an embedded device, or as a surface-mounted component.

Unlike conventional batteries, thin film batteries can be deposited directly onto chips or chip packages in any shape or size, and when fabricated on thin plastics, the batteries are quite flexible. Some of the unique properties of thin-film batteries that distinguish them from conventional batteries include: all solid state construction; can be operated at high and low temperatures (tests have been conducted between -20°C and 140°C); can be made in any shape or size; cost does not increase with reduction in size (constant $/cm²); completely safe under all operating conditions.

Because of their unique features, thin-film batteries have a wide range of uses as power sources for consumer and industrial products such as non-volatile memory, semiconductor diagnostic wafers, smart cards, sensors, radio frequency identification tags, and medical products such as implantable defibrillators and neural stimulators. The small size of this new battery technology will improve existing consumer and medical products and enable the development of many new products.
The construction of a thin film solid state battery is illustrated by the schematic. The different layers are deposited by sputtering or evaporation, methods which are commonly used in the semiconductor and optical coating industries. For more on thin film batteries...

Friday, December 7, 2007

Diamond Coating Protects Retinal Implant

A design of an implantable electronic device always takes into consideration the coating, as it is the only barrier that protects the gadget from fluids and from the natural immune responses of the body. Designing a protective coating for miniature electronics is an extremely difficult endevour. The silicon chip retinal implant is being developed by Second Sight, a company based in Sylmar, California, along with a consortium of university researchers. The device needs a hermetic case to prevent it from reacting with fluids in the eye. Researchers have developed an ultrananocrystalline diamond (UNCD) film that is guaranteed to be safe, long-lasting, electrically insulating and extremely tough. The coating can also be applied at low temperatures that do not melt the chip's microscopic circuits. The UNCD film is the first coating to meet all the necessary criteria for the implant, says Xingcheng Xiao, a materials scientist at Argonne National Laboratory, Illinois, who developed the film. The tiny diamond grains that make up the film are about 5 millionths of a millimetre across. They grow from a mixture of methane, argon and hydrogen passing over the surface of the five-millimetre-square chip at about 400 C. Xiao and his colleagues have already tested the implants in rabbits' eyes, and saw no adverse reaction after six months.

Vanadium Dioxide Thin Film Switches Between Reflective and Transparent

A new study reports that a laser can be used to switch a film of vanadium dioxide back and forth between reflective and transparent states without heating or cooling it. It is also among the most recent examples of “coherent control,” the use of coherent radiation like laser light to affect the behavior of atomic, molecular or electronic systems. The technique has been used to control photosynthesis and is being used in efforts to create quantum computers and other novel electronic and optical devices. The new discovery opens the possibility of a new generation of ultra-fast optical switches for communications. The study, which was published in the Sept. 18 issue of Physical Review Letters, was conducted by a team of physicists from Vanderbilt University and the University of Konstanz in Germany headed by Richard Haglund of Vanderbilt and Alfred Leitenstorfer from Konstanz.

Vanadium dioxide’s uncanny ability to switch back and forth between transparent and reflective states is well known. At temperatures below 154 degrees Fahrenheit, vanadium dioxide film is a transparent semiconductor. Heat it to just a few degrees higher, however, and it becomes a reflective metal. The semiconducting and metallic states actually have different crystalline structures. Among a number of possible applications, people have experimented with using vanadium dioxide film as the active ingredient in “thermochromic windows” that can block sunlight when the temperature soars and as microscopic thermometers that could be injected into the body.

The vanadium dioxide thin films were created useing ultrafast infrared laser deposition. The researchers have determined the molecular mechanism behind this effect:

Thursday, December 6, 2007

How a Successful CEO Talks

Martin Roscheisen, CEO of thin film solar company Nanosolar, founded the startup five years ago when solar was nowhere near the hot topic it is today. Sitting on a profoundly transformative new thin film solar technology and with great leadership, Nanosolar is the one to watch. Read the interview and be impressed.

Saturday, December 1, 2007

Diamond Scratch-Resistant Coating for Luxury Mobile Phones

Diamond thin films are an extraordinary material with the potential to have enormous global economic impact. ThinFilmsBlog will be reporting on state-of-the-art diamond film technology and applications. It is significant that although the Diamondshield coating is relatively soft (2-3 GPa versus up to 75 GPa for non-hydrogenated, tetrahedral amorphous carbon: ta-C) this film none-the-less provides valuable benefit in this application. It shows how much room for improvement there still is for diamond film technology.

North American manufacturer of luxury mobile phones, Mobiado, is using a scratch-resistant coating on the front face of its exclusive Luminoso 3G phone. The new DiamondShield coating gives polycarbonate and acrylic screens a previously unattainable scratch-resistance that is comparable to glass, while maintaining the weight savings, impact resistance, formability and other benefits of plastic.

DIAMONEX produces Diamond-Like Carbon (DLC)and related coatings by both Ion Beam and RF Plasma CVD deposition processes operating under vacuum at substrate temperatures typically <150° C.