1. Heater temperature 700 C.
2. The RHEED oscillations were monitored after the heater reached the target temperature.
3. We are using an AC power supply, SiC heater element, with a PID controller.
4. The substrate already had some deposited layers of STO from earlier deposition.
5. There is a suspicion that the oscillations are due to magnetic field changes because of heater current changes due to PID steady state oscillations
Certainly using DC power for your heater is a must. Also the design of the SiC heating element is important. It should be designed so that adjacent lines cancel out magnetic fields.
Turn the heater off and see if you have oscillations. If you don't you can assume it is the AC
If AC current was causing the oscillations, wouldn't the oscillations be at 50Hz. Here the frequency of oscillations is 0.1Hz. Then there must be something else going on.
Have you come across PID controllers oscillating once they reach the set temperature?
RHEED oscillations can be seen also if the surface evaporates layer by layer, not only when the material is deposited in this mode. To test this possibility, I may suggest trying to change the substrate temperature (and wait for temperature stabilization, of course). If the oscillation period shortens increasing substrate temperature by e.g. 20-50 degC (so increasing the intensity of evaporation) that's it (and opposite, if the period extends when you decrease surface temp.).
Regards,
Tom
I think it is unlikely that SrTiO3 would be evporating at 700 C. It is possible that the PID of the temperature controller has a 10 second cycle time turning the power on and off for temperature control. Simple shut the power off and see what happens.
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