Barrier coatings
A secondary electron emissive layer resistant to infiltration and fouling. A barrier layer is formed by atomic layer deposition. The barrier layer may be an emissive layer and/or an interlayer. The barrier layer may form an interlayer that is a part of an electron amplifier positioned between an emissive layer and a resistive layer. The barrier layer is resistive to fluorine migration from either the emissive layer or the resistive layer.
1. An electron detector device comprising:
a microchannel plate having a plurality of channels extending therethrough;
a resistive layer deposited on the microchannel plate;
an emissive layer deposited on the resistive layer; and
an interlayer deposited between the resistive layer and the emissive layer;
wherein the interlayer comprises a metal oxyfluoride; and
wherein the metal oxyfluoride is MgO x F y , where x is greater than 0 and less than 1 and y is greater than 0 and less than 2(1−x).
2. The electron detector of claim 1 , wherein the interlayer and the emissive layer are comprised of the same material.
3. A method of forming an electron amplifier comprising:
providing an electron amplifier substrate, having a resistance, within an atomic layer deposition reactor; and
depositing a barrier layer selected from a group comprising Al 2 O 3 , MgF 2 , CaF 2 , MgO x F y , where x is greater than 0 and less than 1 and y is greater than 0 and less than 2(1−x), by an atomic layer deposition process including at least one cycle of:
pulsing a first metal precursor into the reactor for a first metal precursor pulse time;
purging the reactor of the first metal precursor;
pulsing a second precursor into the reactor for a second precursor pulse time; and
purging the reactor of the second precursor.
4. The method of claim 3 , wherein the electron amplifier substrate further comprises a resistive layer comprising a fluoride.
5. The method of claim 3 , wherein depositing the barrier layer comprises depositing an interlayer on the electron amplifier substrate and an emissive layer on the interlayer.
6. The method of claim 3 , wherein the interlayer and the emissive layer are comprised of the same material.
7. The method of claim 3 , wherein the barrier layer comprises Al 2 O 3 and is deposited on the resistive layer.
8. The method of claim 7 , further comprising depositing an emissive layer on the barrier layer of A 1 2 O 3 by an atomic layer deposition process.
9. The method of claim 8 , wherein the resistive layer comprises W:AlOF.
10. The method of claim 9 , wherein the emissive layer comprises MgO.
11. The method of claim 5 , wherein the barrier layer of Al 2 O 3 comprises a thickness between 1 and 10 nm.
12. The method of claim 5 , wherein the ratio of the barrier layer of Al 2 O 3 to W:AlOF resistive layer is between 1:2 to 1:5000.
13. The method of claim 5 , wherein the ratio of the barrier layer of Al 2 O 3 to MgO resistive layer is between 1:1 to 1:500.
14. The method of claim 3 , wherein the first metal precursor is selected from the group consisting of trimethyl aluminum, aluminum trichloride, tris(dimethylamido) aluminum, aluminum isopropoxide, and dimethyl aluminum isopropoxide.
15. The method of claim 3 , wherein the first metal precursor is selected from the group consisting of Bis(cyclopentadienyl)magnesium, Bis(ethylcyclopentadienyl)magnesium, Bis(N-t-butyl-N′-ethylpropanimidamidato)magnesium, Bis(N,N′-di-sec-butylacetami dinato)magnesium, and Magnesium tetramethylheptanedionate.