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Atomic Layer Deposition for Microchannel Plates. Jeffrey Elam Argonne National Laboratory September 24, 2009. Atomic Layer Deposition (ALD). Layer-by-layer thin film coating method Atomic level control over thickness and composition Precise coatings on 3-D objects - PowerPoint PPT Presentation
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Atomic Layer Depositionfor Microchannel Plates
Jeffrey Elam
Argonne National Laboratory
September 24, 2009
Atomic Layer Deposition (ALD)
Layer-by-layer thin film coating method Atomic level control over thickness and composition Precise coatings on 3-D objects Deposit nearly any material (oxides, nitrides, metals, etc.)
Example:ALD Zinc Oxide in
deep trenches
Large Area Photodetector
Microchannel Plate (MCP)
– Electron amplifier (x104-107)
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Microchannel Plates (MCPs)
Conventional Fabrication:– Draw glass fiber bundle– Slice and polish– Chemical etch, heat in hydrogen
Problems:– Expensive– Resistance and secondary emission properties are linked– Long conditioning process needed– Thermal runaway
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ALD for Fabrication of MCPs
Start with porous, insulating substrate
– Glass capillary plate
– Anodic aluminum oxide (AAO) membrane ALD of resistive film on all surfaces (inside of pores, on faces, etc.) ALD of secondary electron emissive film Deposit metal electrodes on outer surfaces
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33 mm
MCP Structure
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1) resistive coating (ALD)2) emissive coating (ALD)3) conductive coating (thermal
evaporation or sputtering)
pore
ALD for Resistive Coating
Target: 10-100 MΩ through MCP ZnO: conductor Al2O3: insulator
ZnO/ Al2O3 alloy – tunable resistivity
Tune composition and thickness of film to adjust MCP resistance
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ALD for Emissive Coating
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Many material possibilities Tune SEE along pore
SiO2Al2O3
MgO
ZnO
Cross-Sectional Elemental Maps of ALD MCP
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Zn
SEM Si
Al Au
ALD ZnO and Al2O3 extend into pores
Sputtered Au only on edge of pores
Glass capillary plate ALD ZnO/Al2O3
Sputter gold electrodes
Cross-Sectional Image of ALD Film in MCP
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ALD Film
100 nm ALD film visible in middle of MCP
Glass
Questions?
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