Conclusions TEM analysis shows dislocations and imperfections in superlattice structure Defects present in used sample near surface SRIM depth analysis shows implantation likely SIMS analysis shows residual gas species in near surface region: Fluorine prevelant Future Studies •Be dopant and P distribution: Oxygen SIMS •Heating alone vs. ion damage Reference F.A. Stevie et al., Surf. Interface Anal. 2001 31 345. Superlattice Photocathode Damage Marcy Stutzman and the Center for Injectors and Sources Transmission Electron Microscopy (TEM) • Samples prepared by focused ion beam milling • TEM analysis of structure Polarization constant through many activations Increasing SCL with use Install Sept 13, 07 Re-heat 28Dec07, 5Mar08, 18Mar08 Secondary Ion Mass Spectrometry Monitors species as a function of depth Surface Analysis Goals Which residual gasses limit photocathode lifetime? Why do we have surface charge limit? Why does SCL get worse with photocathode age? Does Be dopant migrate with heat cycles? Unused Used Used Focused Ion Beam mills cross sectional depth profile Fred Stevie NCSU Defects Au-Pd Pt 100 nm superlattice Implantation depth calculation 100 kV: Ar,F,O,C 60-200 n <10 kV: H implants 100 nm Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05- 06OR23177. Orange data sets: used sample Blue data: unused sample
Superlattice Photocathode Damage Marcy Stutzman and the Center for Injectors and Sources
Jan 22, 2016
Surface Analysis Goals Which residual gasses limit photocathode lifetime? Why do we have surface charge limit? Why does SCL get worse with photocathode age? Does Be dopant migrate with heat cycles?. - PowerPoint PPT Presentation
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ConclusionsTEM analysis shows dislocations and imperfections in superlattice structureDefects present in used sample near surface SRIM depth analysis shows implantation likelySIMS analysis shows residual gas species in near surface region: Fluorine prevelant
Future Studies•Be dopant and P distribution: Oxygen SIMS•Heating alone vs. ion damage
ReferenceF.A. Stevie et al., Surf. Interface Anal. 2001 31 345.
Superlattice Photocathode DamageMarcy Stutzman and the Center for Injectors and Sources
Transmission Electron Microscopy (TEM)• Samples prepared by focused ion beam milling• TEM analysis of structure
Polarization constant through many activations
Increasing SCL with use Install Sept 13, 07 Re-heat 28Dec07, 5Mar08, 18Mar08
Secondary Ion Mass Spectrometry Monitors species as a function of depth
Surface Analysis Goals Which residual gasses limit photocathode lifetime? Why do we have surface charge limit? Why does SCL get worse with photocathode age? Does Be dopant migrate with heat cycles?
UnusedUsed Used
Focused Ion Beam mills cross sectional depth profile
Fred Stevie NCSU
Defects
Au-Pd
Pt
100 nm superlattice
Implantation depth calculations 100 kV: Ar,F,O,C 60-200 nm <10 kV: H implants 100 nm
Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Orange data sets: used sample
Blue data: unused sample
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