1. + Analysis of Anomalous Film Growth when Yttrium Oxide Thin Films are Exposed to 7.2eV Light Alison Wells Dr. David D. Allred Devon Mortenson Kristal Chamberlain

2. + Background Group members took some samples to Berkeley for measurements using the Advanced Light Source. When they got back needed to put it in the plasma cleaner. Why? Because there is a sort of “gunk” composed mainly of hydrocarbons deposited on samples. Problem: the plasma cleaner was broken. Solution: Use the excimer (VUV) lamp instead.

3. + Background Continued After approximately 5 minutes under the VUV lamp, the sample became visibly thicker. Use ellipsometry measurements to determine if this is true. The Mystery

4. + Ellipsometry Measurements: Y2O3 Before cleaning: 24.94 nmAfter 5 min VUV: 31.061 nm

5. + In Search for an Answer Big question is: What’s going on here?

6. + First Theories First thought: the yttrium is not fully oxidized. Too thick Is it possible that the VUV lamp is actually depositing material onto the sample? Not possible that more Y 2 O 3 is being added to film. Subject a blank silicon substrate to same VUV treatment and look for film deposition. No growth

7. + First Set of Conclusions Oxidation of Silicon Substrate Thickness decreases in furnace Only other option is that what is already on the film is somehow being altered. It doesn’t seem likely that the VUV lamp is depositing material onto our film.

8. + Second theories and Tests (cont.) Necessity of VUV Interaction with Sample

9. + Second theories and Tests (cont.) Necessity of an ozone

10. + Look at Neighboring Oxide What would happen to a scandium oxide when exposed to same VUV treatment. New Theories

11. + Comparing Oxides May be slightly hydroscopic Reactively Sputtered sample Insoluble in water Natural oxidation vs. reactive sputtering Y2O3Sc2O3 Water in the voids

12. + Ellipsometry Measurements: Natural Oxidized Sc2O3 Before VUV: 22.842 nmAfter 40 min: 23.310 nm

13. + Ellipsometry Measurements: Reactively Sputtered Sc2O3 Before Cleaning: 12.528 nmAfter 5 min VUV: 13.218 nm

14. + Ellipsometry Measurements: Reactively Sputtered Sc2O3 After 10 min VUV: 14.406 nmAfter 20 min VUV: 15.524 nm

15. + Ellipsometry Measurements: Reactively Sputtered Sc2O3 After 40 min VUV: 17.902 nmAfter 70 min VUV: 17.203 nm

16. + The Mystery Continues Thicker Films Use XPS to look at oxygen to metal ration Observe other oxides Deposit Silicon cap over samples Future Work

17. + Thank You Brigham Young University Physics Department Dr. David D. Allred BYU Thin Film Optics Research Group