getter

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getter

[′ged·ər]
(chemistry)
(physical chemistry)
A substance, such as thallium, that binds gases on its surface and is used to maintain a high vacuum in a vacuum tube.
A special metal alloy that is placed in a vacuum tube during manufacture and vaporized after the tube has been evacuated; when the vaporized metal condenses, it absorbs residual gases. Also known as degasser.

getter

In vacuum or gas-filled tubes, it is a small, ring or cup-shaped device containing a powdered metal that reacts strongly to oxygen. When the tube is sealed, the getter is fired (heated) to further evacuate a vacuum tube or to remove impurities from the gas. Firing causes the getter material to oxidize and absorb any free oxygen in the tube, which would otherwise oxidize the active electrodes and decrease the tube's life. Tubes with graphite-based electrodes do not use getters, because the graphite itself absorbs oxygen.

In a vacuum tube, the location of the getter is sometimes identified by a shiny silver deposit behind the glass, which is residue from the firing. The metal used in the getter depends on tube manufacturer, type and composition. Barium is an excellent oxygen absorber and is used in tubes with a fired getter. Zirconium and titanium, also used as getter material, oxidize from the tube's self-generated heat and do not require firing.
References in periodicals archive ?
The NanoGetters technology developed by ISS uses a proprietary set of materials that are precisely vacuum deposited, providing an alternative solution to traditional non-evaporative gettering technology.
Pichler presents students, academics, researchers, and professionals working in a wide variety of contexts with a collection of peer-reviewed papers selected from research presented at the Gettering and Defect Engineering in Semiconductor Technology conference held in September of 2015 in Germany.
A breakthrough in getter pump technology occurred when it was found that by alloying the basic getter elements like zirconium with other ones, it was possible to "modulate" some of their characteristics for the gettering process.
Because iGEM(TM) enhances gettering at various levels of low resistivity, it should help device makers improve yields at the current resistivity levels they're working with, and be able to move to lower resistivity without sacrificing yield.
The engineered improvements in iGEM(TM) complement conventional techniques that increase gettering in low resistivity wafers -- techniques like thin films and backside damage.
These gettering materials must function adequately while being extremely small and free of loose particles and thin enough to meet the ever-shrinking packaging requirements of MEMS.
MDZ(TM) treated wafers also provide two other major device- manufacturing advantages: MDZ(TM) provides reliable internal gettering at lower thermal budgets, and it allows the elimination of several costly steps at the beginning of the device manufacturing process.
The common thread that runs through these gettering systems is that they all are relatively low-through-put devices that are more suited for clean UHV processes, where gas loads are low.
Thin films of getter material are deposited on host surfaces, such as a chamber wall, where the gettering action takes place.
As in all gettering systems, a solid-state getter material has a finite ability to sorb gases before it becomes saturated.
Oil-sealed mechanical pumps, then, required an additional high-vacuum pump, such as a turbomolecular pump, to reach lower pressures before gettering could be started.
MDZT treated wafers also provide two other major device- manufacturing advantages: MDZT provides reliable internal gettering at lower thermal budgets, and it allows the elimination of several costly steps at the beginning of the device manufacturing process.