1 / 14

Characterization Plans

Characterization Plans. Slade J. Jokela, I. Veryovkin, A. Zinovev. Secondary Emission Materials. We have mainly focused on MgO and Al 2 O 3 We should examine other materials as well as structures (primarily layered materials)

blocklear
Télécharger la présentation

Characterization Plans

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Characterization Plans Slade J. Jokela, I. Veryovkin, A. Zinovev

  2. Secondary Emission Materials • We have mainly focused on MgO and Al2O3 • We should examine other materials as well as structures (primarily layered materials) • Looking for non-conducting materials with high electron backscatter. • Find optimal thickness for MgO (or other material) then place an electron ‘reflecting’ layer just underneath • This would essentially make use of primary electrons that penetrate further than the maximum escape depth for secondary electrons

  3. Examine ‘New’ Materials/Structures • While it appears that MgO provides excellent emission capabilities, there are other materials/structures to try • MgO/TiO2 or MgO/CaO mix • Shows an increase in emission over MgO alone • Suspected that band structure change due to increased oxygen to cation ratio is responsible (for TiO2) • Diamond • First strike material (can’t be deposited deep in channel)

  4. Electron Backscatter • High Z materials • Tungsten is a candidate • Will take a survey of samples and see if there are MgO samples on W that aren’t too thick • Thickness of backscatter layer will certainly play a role Material With Large Backscatter Yield MgO Conductive Si

  5. Electron Beam Pulsing • I’m confident that I have figured out how to properly pulse electron beam with current equipment • Need a Trigger-Link cable for Keithley Meters (proprietary?) • Still need to write a Labview VI, but this can’t be tested until I get the trigger cable

  6. Continued Thickness Series • Need to repeat MgO thickness series on new LEED system (reproducibility) • Will need to repeat again once pulsing is enabled (accuracy) • Need Al2O3 samples to compare • Will anneal some samples and reexamine results

  7. CO2 Snow Cleaning • Will begin this experiment in the next two weeks • Comparing microscopic images between cleaned and uncleaned MCPs (looking for clogged pores) • Eventually will test MCPs after ALD coating to determine if cleaning will improve the final product

  8. Photocathodes • Sample carousel (4 position) designed • Photocathode position • Rotation axis of carousel contains a prism that will direct light from a chamber window to the back side of the transmission photocathode • Heater position • 20 Watt quartz lamp will be directed to heat the sample • Remaining positions are open • One may contain a faraday cup • Other may just be for high voltage applications

  9. Mass Spectrometry • Still pursuing a mass spectrometer • Necessary for accurate studies of scrubbing (electron stimulated desorption) • Temperature-programmed desorption (20 W quartz heater) • What does heat-treating samples actually do? • What temperature is necessary to treat the sample and why? • What material is removed that improves the sample? • Secondary Neutral Mass Spectrometry (SNMS) • Post-sputter ionization of material using electron impact • Useful for depth profiling where material isn’t easily ionized by ion beam • Should be better at depth profiling photocathodes

  10. XPS/UPS/SEY Chamber Transfer Chamber Mass Spectrometer Chamber

  11. 4-Position Sample Carousel Additional 20W Heater in this holder

  12. Photocathode Holder Prism for Transmission Photocathodes

More Related