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posted by mrpg on Saturday July 15 2017, @01:30AM   Printer-friendly
from the think-of-the-vacuum-tubes dept.

Imec researchers have described a method of creating smaller transistors using materials such as 2D black phosphorus (phosphorene):

Designers can extend Moore's Law scaling beyond the 5-nanometer node by choosing two-dimensional anisotropic (faster with the grain) materials such as monolayers of black phosphorus, according to Imec (Leuven, Belgium). Researchers from the nonprofit semiconductor research institute described their findings at the annual Imec Technology Forum, held in San Francisco on the eve of Semicon West (July 11-13).

Imec's demonstration project focused on field-effect transistors for high-performance logic applications as part of its Core CMOS program. Using co-optimization at the material, device, and circuit levels, Imec and its collaborators proved the concept using 2-D monolayers of anisotropic black phosphorus with a smaller effective mass in the transport direction. The black phosphorus was sandwiched between interfacial layers of low-k dielectric, with stacked dual gates deployed atop high-k dielectrics to control the atomically thin channels.

Imec demonstrated the co-optimization approach at the 10-nm node but says the architecture could function with sub-half volt (<0.5-V) power supplies and an effective oxide thickness of less than 50 angstroms (0.5 nm), allowing its FETs to extend Moore's Law for high-performance logic applications below the 5-nanometer node.


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  • (Score: 2, Interesting) by Anonymous Coward on Saturday July 15 2017, @02:35AM (2 children)

    by Anonymous Coward on Saturday July 15 2017, @02:35AM (#539441)

    Ever wonder why the button/brush/wiper in a variac doesn't short out the thing?
    It is of this sort of stuff.

    Transformers - The Variac [whsites.net]
    The term "Variac" (from "vary AC") has become generic, and commonly refers to any continuously variable autotransformer.
    [...]
    The Variac is a special type of transformer, generally having a single winding and a single layer. The top section of the winding is flattened and machined to remove the insulation and provide a smooth surface for the sliding brush that's used to select the voltage needed.
    [...]
    The sliding brush deserves special comment. It is almost invariably made from carbon, in the form of graphite. The brush commonly spans at least two turns, and sometimes more. The small Powerstat unit's brush can span three turns. It would seem that if the brush spans two or more turns, it should form shorted turns, causing huge current flow and causing the transformer to burn out.

    Fortunately, graphite is an anisotropic material, having very different resistivity depending on the direction of current vs. the alignment of the graphite planes. A direct measurement across the brush of the Powerstat transformer gives a resistance of about 6 ohms, but this is reduced to ~1.5 ohms in the plane that joins the winding to the wiper arm. This means that each winding is basically feeding a resistor network that limits the maximum "shorted turn" current to a harmless level. The resistor "network" also helps average the voltage between turns, so instead of voltage steps, the output is more or less continuously variable.

    The variation of resistance between the transverse (across the brush) and longitudinal (windings to wiper arm) directions depends on the specific graphite compound, and can range from 1:1 to as much as 10:1 respectively. It can be higher, but this makes the graphite compound too brittle, so it may shear during use.

    -- OriginalOwner_ [soylentnews.org]

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  • (Score: 2) by kaszz on Saturday July 15 2017, @02:45AM (1 child)

    by kaszz (4211) on Saturday July 15 2017, @02:45AM (#539444) Journal

    Fortunately, graphite is an anisotropic material, having very different resistivity depending on the direction of current vs. the alignment of the graphite planes.

    Neat!

    I suppose the resistance is dependent on the physical electron direction in the graphite material and not the direction of current?

    • (Score: 0) by Anonymous Coward on Saturday July 15 2017, @08:55PM

      by Anonymous Coward on Saturday July 15 2017, @08:55PM (#539648)

      Graphite is basically stacked flat sheets of carbon atoms in an hexagonal pattern. Low resistance is along the sheets, high resistance is across the stack, so really it is a good conductor in two dimensions and a poor one in the third.