In situ oxidation

In 2014, Erica and I were trying to do an in situ oxidation procedure. The idea was that the oxide grown in situ would protect the Bi film from further oxidation, and form a smoother / more controllable top surface on the film. It turned out that the ex situ native oxide is also apparently self terminating, and that it doesn't seem to prevent observation of the surface states in Bi magnetotransport, so we stopped doing this.

In 2017-2018, I started growing BiSb, and realized that the Sb oxidizes faster than Bi, making the situation a little more complicated. I think that in BiSb(012) films, oxidation is probably more significant than in Bi(001), due to both the larger Sb % and the higher density of broken bonds on the (012) surface. Additionally, the thin native oxide is more significant in nanoscale films with the A17 structure. It's unclear what the oxidation situation might be for the Sb films I'm growing for Prof Palacios.

Here's the 2014 procedure in case it's needed again in the future.

• As of 2018 the O2 leak valve is only installed on Bravo

• Make sure trolley is in LC

• If other people's samples are for some reason on the trolley, make sure they are stored in the BC. Don't oxidize other people's samples.

• Close LC / BC GV

• Record LC pressure

• Use O2 leak valve to raise LC pressure to 1E-6 by turning both leak valve knobs together 2 full turns counter clockwise

• Optionally turn on LC lamp

• Wait for 1 hour

• Close leak valve, wait for LC pressure to return to original value

• Load / unload samples for next grower

Note - as of 2014, improper leak valve closing resulted in a large amount of O2 stored in the O2 line, not in the tank, which is why this procedure does not mention opening the tank. As of 2018, I'm not sure about the current situation. You may need to open the O2 tank as well. If you do, please make sure you close off the tank first and then close the O2 valve, to avoid trapping O2 in the line.