Dear Inma Ortega , Kurt Lesker company recomends 10-6 Torr or lower with an evaporation temperature of 1400ºC. It is important how much you fill the crucible, they recomended 67-75% of crucible volume, to avoid spills.

They also shows a couple of pressures more and the temperatures but the previous is the best recipe.

Here is the link with relevant information:

https://www.lesker.com/newweb/deposition_materials/deposition-materials-notes.cfm?pgid=ge1

Hope it helps!

Sanchette, F., C. Ducros, A. Billard, C. Rébéré, C. Berziou, M. Reffass, and J. Creus. "Nanostructured aluminium based coatings deposited by electron-beam evaporative PVD." Thin Solid Films 518, no. 5 (2009): 1575-1580.

Dear Manuel Gómez , thank you vey much!! It helps a lot, thank you. I just have one more question:

I understand that base pressure is the one before starting the evaporation, am I right? I was wondering which was the pressure to evaporate Ge during the measure. Because of that I said that 1e-5 torr could be sufficient in my question. Unfortunately, I don't know the relationship between vapor pressure or Temperature and voltage of the chamber, as I am quite new in the field. May be if you know this I could make and approximation.

Do not hesitate to correct me if I am assuming something wrongly, please

Thank you very much!

Dear Dr Azeez Barzinjy , thank you! I will look at it

Dear Inma Ortega , the base pressure is the one that really matters to achieve evaporation of the material at the conditions of operation. However, your question is totally reasonable, when the material starts to evaporate the pressure inside the chamber rises (the vacuum drops). How much? In my experience around 1 order of magnitude, but probably it depends on the operation conditions, material to be deposited etc. Initially the change is more strong, but then it recovers a bit.

So, if your base pressure is 10-5 torr the operative pressure while deposition will be higher -say 10-4 torr- .

After a quite extensive search I didn´t find any concern about the pressure rise during evaporation, both in scientific papers or technical brochures from the manufacturers.

Most e-beam deposition systems include a PID controller (Proportional-Integral -Derivative controller, or three-term controller, that is a feedback loop, to keep the conditions of operation constant during the process. I thought it could also deals with the chamber´s pressure, but apparently it pay attention mainly to the evaporation rate and beam conditions.

Some companies make vacuum controllers that allow automatic vacuum control, for example:

https://e-beam.ferrotec.com/products/e-beam-controllers/ferrovac-vacuum-controller/

I found a 2016 PhD thesis from UPM by Penyun Huo, where he deals with e-beam deposition of multiple materials, including Ge, that could be useful for your work too. They used a Ferrotec machine and it was what lead me to the previous link.

http://oa.upm.es/42343/1/PENGYUN_HUO.pdf

About the relationship between VP, Temp and Voltage, my be this link might be useful:

http://users.wfu.edu/ucerkb/Nan242/L06-Vacuum_Evaporation.pdf

Here you also can see the tables with evaporation conditions for different elements.

About depositing Ge at 10-5 I have found some e-beam sources that apparently can do the job, they use sources with arc-suppression:

https://telemark.com/electron-beam-sources/arc-suppression-upgrade/

Hope it helps.

Best!

Thanks a los, Manuel Gómez !!

We tried it with base pressure of 2E-7 torr and it increased up tu E-5. Thank you also for the curves, they have been very useful!