- Source: IEEE Circuits, September Newsletter, By: Sylvie Barak, The Inquirer
FANS OF ELECTRON mobility research rejoice! Boffins at Germany’s Physikalisch Technische Bundesanstalt (PTB) have come up with a brand spanking new high-vacuum semiconductor crystal generation process which purports to produce crystals five times purer than all previous known epitaxy systems.
PTB’s new system apparently relies on an innovative molecular beam epitaxy system, with GaAs (gallium-arsenide) and AlGaAs (aluminum-gallium-arsenide) semiconductor heterostructures forming a base. These are then evaporated in a vacuum and laid down in atomic layers, only a few nanometers thin. These then form an electron layer within the crystals, called a two-dimensional electron gas.
Mobility of electrons depends quite significantly on lowering the amount of impurities, so, to mop up the nasty stuff, the boffins have added special cooling panels to suck up any unwanted waste.
To generate the crystals themselves, a special ultrahigh vacuum is used. At 15 orders of magnitude beneath standard atmospheric pressure, you could say, it sucks. Big time. It is also, by no means, an easy feat and requires multiple stages of vacuum creation, starting with partial vacuums and moving up.
Once the vacuum has been formed, the molecular-beam epitaxy gets going, allowing the incredibly pure crystals to form using the aforementioned layering system.
All this, ultimately, leads to a much purer form of semiconductor, which is good news for Chipzilla and Moore’s Law advocates, as well as to those looking into things like quantum Hall resistance metrology and new thinking on electrical current as a function of frequency and electron charge.
Exciting stuff indeed.
PTB’s new system apparently relies on an innovative molecular beam epitaxy system, with GaAs (gallium-arsenide) and AlGaAs (aluminum-gallium-arsenide) semiconductor heterostructures forming a base. These are then evaporated in a vacuum and laid down in atomic layers, only a few nanometers thin. These then form an electron layer within the crystals, called a two-dimensional electron gas.
Mobility of electrons depends quite significantly on lowering the amount of impurities, so, to mop up the nasty stuff, the boffins have added special cooling panels to suck up any unwanted waste.
To generate the crystals themselves, a special ultrahigh vacuum is used. At 15 orders of magnitude beneath standard atmospheric pressure, you could say, it sucks. Big time. It is also, by no means, an easy feat and requires multiple stages of vacuum creation, starting with partial vacuums and moving up.
Once the vacuum has been formed, the molecular-beam epitaxy gets going, allowing the incredibly pure crystals to form using the aforementioned layering system.
All this, ultimately, leads to a much purer form of semiconductor, which is good news for Chipzilla and Moore’s Law advocates, as well as to those looking into things like quantum Hall resistance metrology and new thinking on electrical current as a function of frequency and electron charge.
Exciting stuff indeed.
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