Database of materials; lift-off lithography; silicon photonics project.
Materials database
The Department of Energy’s Lawrence Berkeley National Laboratory has published a study that quantifies the thermodynamic scale of metastability of some 29,902 materials.
To quantify the materials, researchers used Berkeley Lab’s Materials Project, a large and open database of known and predicted materials. The open and Web-based database has calculated the properties of more than 67,000 materials. These materials involve inorganic compounds, bandstructures, molecules, among others.
The Materials Project is a tool for researchers. Using supercomputers to calculate the properties of these materials and data mining to find them, the Materials Project helps researchers to remove the guesswork from the development of materials. Materials are used in various applications, such as pharmaceuticals, semiconductors and others.
The plots show the thermodynamic metastability for the Group VI chemistries (Credit: Ceder Group/Berkeley Lab)
Metastable materials are materials that transform to another state over a period of time, according to researchers from Berkeley Lab. “In physics, metastability denotes the phenomenon when a dynamical system spends an extended time in a configuration other than the system’s state of least energy,” according to Wikipedia.
Metastable phases are common, but researchers only have a basic understanding of the technology. Previously, researchers only had the thermodynamic numbers for less than 1,000 metastable compounds, according to Berkeley Lab.
“There’s a great amount of possibility in the space of metastable materials, but when experimentalists go to the lab to make them, the process is very heuristic—it’s trial and error,” said Wenhao Sun, a researcher at Berkeley Lab. “What we’ve done in this research is to understand the metastable phases that have been made, so that we can better understand which metastable phases can be made.”
Sun added: “We’re essentially proposing search criteria⎯we’re identifying which crystalline materials can be made, and possibly under what conditions they can be made. We hope this can be a more refined way to think about which crystal structure nature chooses when a material forms.”
Lift-off lithography
The Chalmers University of Technology and others have put a new spin on a lithographic technique called lift-off.
Using a multiscale conformal pattern transfer or lift-off process, the technology can pattern a feature on any surface or object. The object could also be three dimensional as well.
There are several possibilities with this technique. For example, researchers from Chalmers patterned an array of 100nm diameter plasmon nanodisk antennas and transferred them to a glass slide. In other example, 60nm plasmonic nanodisks were transferred onto a conventional light bulb.
In the flow, a pattern is developed on a “parent substrate.” Then, a sacrificial lift-off layer is deposited on the substrate using a deposition tool, according to researchers. Then, a 10nm carbon film is deposited on top using e-beam evaporation. The substrate and film are baked in an argon atmosphere at 500 °C, according to researchers.
Following those steps, the sacrificial layer is removed or lifted off using a wet etch process. This, in turn, creates a pattern on the bottom of the carbon film, according to researchers.
Then, a separate substrate or host substrate is prepared. The host substrate is treated with oxygen plasma. This, in turn, will make it hydrophilic, researchers said. Then, in the parent substrate, the carbon film is removed. It is placed on the host substrate. The residue is etched, thereby creating a pattern on this substrate, they added.
“It works in a rather simple procedure that does not even require a complicated clean-room-type processing,” said. Alexandre Dmitriev, associate professor at the Department of Physics at the University of Gothenburg.
Silicon photonics
Leti, an institute of CEA Tech, has launched a new silicon photonics project.
The effort, part of the European Commission Horizon 2020 project, aims to enable the commercialization of new silicon photonics transceivers. The technology would be used for future data-transmission requirements in data centers and supercomputers.
The Leti-coordinated effort, dubbed the COSMICC project, will combine CMOS electronics and silicon photonics with a new fiber-attachment technique. This, in turn, will provide a performance improvement over current VCSELs transceivers. The technology will address future data-transmission needs that traditional wavelength-division multiplexing (WDM) transceivers cannot meet.
The project’s 11 partners from five countries are focusing on developing mid-board optical transceivers with data rates up to 2.4 Tb/s with 200 Gb/s per fiber using 12 fibers. The devices will consume less than 2 pJ/bit and cost approximately 0.2 Euros/Gb/s.
“By enhancing an R&D photonic integration platform from project member STMicroelectronics, the partners in COSMICC aim to demonstrate the transceivers by 2019,” said project leader Ségolène Olivier of Leti. “We also plan to establish a new value chain that will facilitate rapid adoption of the technologies developed by our members.”
Schematic of COSMICC on-board optical transceiver at 2.4 Tb/s (50 Gbps/wavelength, 4 CWDM wavelengths per fiber, 12 fibers for transmission, 12 fibers for reception. (Source: Leti)
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The shared info at LBL is example of how government funding can yield high rewards across the US & planet, when info is shared, vs hidden internally for proprietary R&D. This is very efficient Fed R&D! Si photonics will help speed up beyond RC limits & help move beyond Moore’s law w higher speeds for selected apps.