Self-gettering differential pump
View Patent ↗A self-gettering differential pump for a molecular beam epitaxy system has a collimator with a length greater than its diameter mounted in front of a source in extended port geometry, wherein the reactant delivered by the source also serves as a gettering agent.
1. A self-gettering differential pump for a molecular beam epitaxy system, comprising:
a collimator having a length greater than its diameter, wherein the ratio between the length and the diameter is about two to seven, wherein the collimator includes a first end and a second end, and wherein the first end is positioned in proximity to the vacuum chamber opening; and
a port positioned in proximity to the second end of the collimator, the port comprising an effusion cell that, when activated, delivers a reactant through the collimator to the vacuum chamber opening, wherein the reactant comprised on or more of Sr, Mg, Ca, Ba, Ti and Zn;
wherein the reactant also serves as an oxygen gettering agent on the inner sidewall of the collimator.
2. The self-gettering differential pump of claim 1 , wherein the reactant is a multi-element source.
3. The self-gettering differential pump of claim 1 , wherein the reactant comprises strontium.
4. A molecular beam epitaxy system, comprising:
a vacuum chamber having an opening; and
a self-gettering differential pump that is in fluid communication with the opening, the pump comprising:
a collimator having a length greater than its diameter, the collimator comprising, a first end and a second end, wherein the ratio between the length and the diameter is about two to seven, and wherein the first end is positioned in proximity to the opening; and
a port positioned in proximity to the second end of the collimator, the port comprising an effusion cell that, when activated, delivers a reactant through the collimator to the opening, wherein the reactant comprises one or more of Sr, Mg, Ca, Ba, Ti and Zn;
wherein the reactant also serves as an oxygen gettering agent on the inner sidewall of the collimator.
5. The system of claim 4 , wherein the reactant is a multi-element source.
6. The system of claim 4 , wherein the reactant comprises strontium.
7. The system of claim 4 , wherein a ratio of length to diameter of the collimator is greater than 10.
8. The system of claim 4 , wherein a ratio of length to diameter of the collimator is from about 2 to about 7.
9. A method of reducing flux instability in a molecular beam epitaxy system, comprising:
operating a self-gettering differential pump that is in fluid communication with an opening of a vacuum chamber,
wherein the pump comprises:
a collimator having a length greater than its diameter, the collimator comprising a first end and a second end, wherein the ratio between the length and the diameter is about two to seven, and wherein the first end is positioned in proximity to the opening, and a port positioned in proximity to the second end of the collimator, the port comprising an effusion cell that, when activated, delivers a reactant through the collimator opening, wherein the reactant comprises one or more of Sr, Mg, Ca, Ba, Ti and Zn;
wherein the reactant also serves as an oxygen gettering agent on the inner sidewall of the collimator.