Specific Process Knowledge/Thin film deposition/Deposition of Zinc: Difference between revisions
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<i> | <i> Except where otherwise stated, this page is written by <b>DTU Nanolab staff</b></i> | ||
[[Category: Equipment|Thin film]] | [[Category: Equipment|Thin film]] | ||
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===XPS of Al films to detect Zn=== | ===XPS of Al films to detect Zn=== | ||
''Measurements made in June/July 2018.'' | ''Measurements made by Rebecca Ettlinger in June/July 2018.'' | ||
XPS was done at Nanolab with the XPS K-alpha using 50 eV and 50 ms dwell per scan. The number of scans per element varied as shown below in the figure captions. We can clearly see that the Zn amount in the Al film decreased and became indetectable after cleaning the chamber. Of course we cannot guarantee that there is no Zn contamination at all, since there is a detection limit for the XPS even with many scans per level. | XPS was done at Nanolab with the XPS K-alpha using 50 eV and 50 ms dwell per scan. The number of scans per element varied as shown below in the figure captions. We can clearly see that the Zn amount in the Al film decreased and became indetectable after cleaning the chamber. Of course we cannot guarantee that there is no Zn contamination at all, since there is a detection limit for the XPS even with many scans per level. | ||
[[File:Al w Zn from 20-06-2018.png|400px|left|thumb|XPS of Al film made before chamber was cleaned after Zn deposition. 10 scans per level. Zn peaks are obvious. The Zn content was up to 10 % in some layers.]] | [[File:Al w Zn from 20-06-2018.png|400px|left|thumb|XPS of Al film made before chamber was cleaned after Zn deposition. 10 scans per level. Zn peaks are obvious. The Zn content was up to 10 % in some layers.]] | ||
[[File:Al wo Zn from 09-07-2018.png|400px| | [[File:Al wo Zn from 09-07-2018.png|400px|left|thumb|XPS of Al film made after chamber was cleaned after Zn deposition and a new crucible was used for Al. 10 scans per level for Al, 30 scans per level for Zn. No Zn peaks are visible.]] | ||
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===Lessons for future thermal deposition of Zn=== | ===Lessons for future thermal deposition of Zn (by Rebecca Ettlinger) === | ||
*It is better to use a crucible rather than a W boat to heat small Zn pellets, as the pellets sometimes jumped out of the boat when they got hot. | *It is better to use a crucible rather than a W boat to heat small Zn pellets, as the pellets sometimes jumped out of the boat when they got hot. | ||
* | *Consider using manual mode as the power level for evaporation was not always consistent and the rate was not constant even at a constant power level. See further below, however. | ||
*We needed about 12-13 % power on the Lesker Nano36 Thermal evaporator to get Zn evaporation. It is best to soak for a long time(e.g., ramping and soaking for more than 5-8 minutes). | *We needed about 12-13 % power on the Lesker Nano36 Thermal evaporator to get Zn evaporation. It is best to soak for a long time(e.g., ramping and soaking for more than 5-8 minutes). | ||
*The thickness /rate measurement may not have been accurate as the crystal monitor looked irregularly coated after the deposition. | *The thickness /rate measurement may not have been accurate as the crystal monitor looked irregularly coated after the deposition. | ||
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More information can be found on the O-drive of the Thin film group under PVD/Thermal evaporator (for Nanolab staff only). | More information can be found on the O-drive of the Thin film group under PVD/Thermal evaporator (for Nanolab staff only). | ||
===Further lessons | ===Further lessons by Chanju Kim=== | ||
''Depositions carried out in October 2018.'' | ''Depositions carried out in October 2018.'' | ||
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It was possible to use an automatic program after some adjustments. A stable deposition rate of 0.5 Å/s was obtained with a max. power of 14.5 % after approx. 15 min of ramping and soaking. Depositions at 0.3 Å/s and 1 Å/s were not stable. The final PID parameters were P 15, I 2 and D 1. | It was possible to use an automatic program after some adjustments. A stable deposition rate of 0.5 Å/s was obtained with a max. power of 14.5 % after approx. 15 min of ramping and soaking. Depositions at 0.3 Å/s and 1 Å/s were not stable. The final PID parameters were P 15, I 2 and D 1. | ||
[[File:Zn dep rates.png|400px|left|thumb|Deposition rate versus power for four different trials with Zn deposition.]] | [[File:Zn dep rates.png|400px|left|thumb|Deposition rate versus power for four different trials with Zn deposition. Work and graph by Chanju Kim.]] | ||
It is important not to use too high power as this will give a very fast increase in the deposition rate once the evaporation is started. For new Zn pellets, an oxide removal run is recommended before the actual deposition. The max power needs to be slightly adjusted for this run (slightly higher than for already-melted pellets). | It is important not to use too high power as this will give a very fast increase in the deposition rate once the evaporation is started. For new Zn pellets, an oxide removal run is recommended before the actual deposition. The max power needs to be slightly adjusted for this run (slightly higher than for already-melted pellets). | ||