Notes:

    The RHEED gun must be outgassed after baking the chamber. The steel protections must be closed over the Beryllium windows.


Equipment:


  • RHEED electron gun controller
  • phosphorous screen
  • video camera
  • diffractometer


Procedure:

  1. Verify that all cables are securely plugged in (one of the focusing cables is often disconnected to avoid collisions with the detector arm of the diffractometer).

  2. Put the video camera properly on the phosphorous screen flange. The red tape should be horizontal, towards the preparation chamber.

  3. Position the diffractometer to see a RHEED pattern: 
    	THETA = 68 degrees  (important for the CHI tuning)
	CHI   = +/- 3 deg   (depending on the sample)
	PHI   = +/- 170 deg (to position the azimuth 
                             you want for diffraction)


  4. Close the steel protections over the Beryllium window to avoid bremstrallung x-ray irradiation outside the windows.

  5. Turn ON the power supply. Push the bottom of HT and emission.

  6. Slowly increase the electron gun voltage to 11 kV. Then slowly increase the filament current to 2.2-2.3 mA (bottom left knob). In case of electrical arcs, repeat with less voltage.

  7. Using the X/Y deflectors, adjust the electron beam position to reach your sample surface.

    If the surface is well-prepared and ordered, you should now observe RHEED diffraction spots on the video camera.


Note: RHEED is rarely used since it is much better to use the X-rays.