Method of fabricating microchannel plate devices with multiple emissive layers
A method of fabricating a microchannel plate includes defining a plurality of pores extending from a top surface of a substrate to a bottom surface of the substrate where the plurality of pores has a resistive material on an outer surface that forms a first emissive layer. A second emissive layer is formed over the first emissive layer. The second emissive layer is chosen to achieve at least one of an increase in secondary electron emission efficiency and a decrease in gain degradation as a function of time. A top electrode is formed on the top surface of the substrate and a bottom electrode is formed on the bottom surface of the substrate.
1. A method of fabricating a microchannel plate, the method comprising:
a. defining a plurality of pores extending from a top surface of a substrate to a bottom surface of the substrate, the plurality of pores having a resistive material on an outer surface that forms a first emissive layer;
b. forming a second emissive layer over the first emissive layer, the second emissive layer having a different material composition than the first emissive layer and being chosen to achieve at least one of an increase in secondary electron emission efficiency and a decrease in gain degradation as a function of time;
c. forming a top electrode on the top surface of the substrate; and
d. forming a bottom electrode on the bottom surface of the substrate.
2. The method of claim 1 wherein the first emissive layer comprises at least one of Al 2 O 3 , SiO 2 , MgO, SnO 2 , BaO, CaO, SrO, Sc 2 O 3 , Y 2 O 3 , La 2 O 3 , ZrO 2 , HfO 2 , Cs 2 O, Si 3 N 4 , Si x O y N z , C (diamond), BN, and AlN.
3. The method of claim 1 wherein the second emissive layer comprises at least one of Al 2 O 3 , SiO 2 , MgO, SnO 2 , BaO, CaO, SrO, Sc 2 O 3 , Y 2 O 3 , La 2 O 3 , ZrO 2 , HfO 2 , Cs 2 O, Si 3 N 4 , Si x O y N z , C (diamond), BN, and AlN.
4. The method of claim 1 wherein the top and bottom electrodes are formed before forming the second emissive layer over the first emissive layer.
5. The method of claim 1 wherein the top and bottom electrodes are formed after forming the second emissive layer over the first emissive layer.
6. The method of claim 1 further comprising depositing a barrier layer over the first emissive layer before forming the second emissive layer.
7. The method of claim 1 further comprising depositing a barrier layer over the second emissive layer.
8. The method of claim 1 further comprising selecting at least one of a thickness and a composition of the second emissive layer to maximize the secondary electron emission efficiency of the microchannel plate.
9. The method of claim 1 further comprising selecting at least one of a thickness and a composition of the second emissive layer to passivate the plurality of pores so that a number of ions released from the plurality of pores is reduced.
10. The method of claim 1 further comprising selecting at least one of a thickness and a composition of the second emissive layer to maximize a signal-to-noise of the microchannel plate.
11. The method of claim 1 further comprising selecting at least one of a thickness and a composition of the second emissive layer to optimize electric field uniformity of the microchannel plate so as to reduce image distortion.
12. The method of claim 1 further comprising selecting at least one of a thickness and a composition of the second emissive layer to form a plurality of charge traps at a material interface between the first and second emissive layers.
13. The method of claim 1 further comprising selecting at least one of a thickness and a composition of the second emissive layer to form a plurality of charge traps at a material interface between the first and second emissive layers, the plurality of charge traps establishing an electric field that increases secondary electron emission efficiency.
14. A method of fabricating a single channel electron multiplier, the method comprising:
a. defining a single channel extending from a top surface of a substrate to a bottom surface of the substrate, the single channel having a resistive material on an outer surface that forms a first emissive layer;
b. depositing a second emissive layer over the first emissive layer, the second emissive layer having a different material composition than the first emissive layer and being chosen to achieve at least one of an increase in secondary electron emission efficiency and a decrease in gain degradation as a function of time;
c. forming a top electrode on the top surface of the substrate; and
d. forming a bottom electrode on the bottom surface of the substrate.
15. The method of claim 14 wherein the second emissive layer comprises at least one of Al 2 O 3 , SiO 2 , MgO, SnO 2 , BaO, CaO, SrO, Sc 2 O 3 , Y 2 O 3 , La 2 O 3 , ZrO 2 , HfO 2 , Cs 2 O, Si 3 N 4 , Si x O y N z , C (diamond), BN, and AlN.
16. A method of fabricating a microchannel plate, the method comprising:
a. drawing a plurality of solid glass fibers, each of the plurality of solid glass fibers comprising a core glass fiber, which is soluble in an etchant, and lead glass cladding that surrounds the core glass fiber, which is not soluble in the etchant;
b. packing the plurality of glass fibers in an array;
c. drawing the packed glass fibers;
d. fusing the drawn packed glass fibers within a glass envelope, thereby forming a boule of packed glass fibers;
e. slicing the boule of packed glass fibers, thereby forming a plate of packed glass fibers;
f. exposing the core glass to the etchant, thereby removing the core glass so that the lead cladding defines a plurality of pores through the plate of packed glass fibers;
g. reducing the lead glass cladding at the surfaces of the plurality of pores in a hydrogen atmosphere to semiconducting lead, thereby forming a first emissive layer at the surfaces of the plurality of pores; and
h. depositing a second emissive layer over the first emissive layer, the second emissive layer having a different material composition than the first emissive layer and being chosen to increase a secondary electron emission efficiency of the microchannel plate.
17. The method of claim 16 wherein the depositing the second emissive layer comprises depositing the second emissive layer using atomic layer deposition.
18. The method of claim 16 wherein the depositing the second emissive layer comprises depositing the second emissive layer by at least one of physical vapor deposition (PVD), thermal evaporation, and chemical vapor deposition (CVD).
19. The method of claim 16 wherein the depositing the second emissive layer comprises depositing at least one of Al 2 O 3 , SiO 2 , MgO, SnO 2 , BaO, CaO, SrO, Sc 2 O 3 , Y 2 O 3 , La 2 O 3 , ZrO 2 , HfO 2 , Cs 2 O, Si 3 N 4 , Si x O y N z , C (diamond), BN, and AlN.
20. The method of claim 16 further comprising depositing a top electrode on a top surface of the plate and a bottom electrode on a bottom surface of the plate.
21. The method of claim 20 wherein at least one of the top and bottom electrodes are deposited before the depositing of the second emissive layer on the first emissive layer.
22. The method of claim 20 wherein at least one of the top and bottom electrodes are deposited after the depositing the second emissive layer on the first emissive layer.
23. The method of claim 16 further comprising depositing a resistive layer on the first emissive layer before the depositing of the second emissive layer.
24. The method of claim 16 further comprising selecting at least one of a thickness and a composition of the second emissive layer to maximize the secondary electron emission efficiency of the microchannel plate.
25. The method of claim 16 further comprising depositing a conducting layer on an outer surface of the plurality of pores before reducing the lead glass cladding material at the surfaces of the plurality of pores.