Association

42 3. Experimental details
electrodes onto an image point, where a Channeltron detector is positioned. The electric
field determining the pass energy is a radial field between the two concentric electrodes, as
schematically shown in Fig. 3.6. For AES, a non-retarding mode is used in which the electrons
pass through the analyzer with their initial kinetic energy, and the energy range being swept
by varying the potential on the outer cylinder. With this geometry, an energy resolution of
0.6% of the electron kinetic energy can be reached, which is limited by the angular deviation
of the incoming electron trajectories (see Lüth (2010)). 79
In this work, AES is employed to routinely check the surface quality by means of chemical
cleanliness, and to quantify the thickness of the in situ oxidation of silicon. A VARIAN
cylindrical mirror analyzer is used with electrons of E exc = 3 keV from a VARIAN 981 e-gun
source. In practice, the energy resolution is ∼1 eV due to the sweep generator.
3.3. Experimental developments at the Oxide-MBE setup
Figure 3.7.: Details of the Oxide-MBE setup at PGI-6. (a): Atomic gas supply with robust tungsten
filament in a high pressure cracking bulb. (b): Oxygen nozzles which are located 10 mm in
front of the sample surface and the mass spectrometer filament. (c): Flashing stage for Si wafer
pieces. Right: Oxide-MBE setup at PGI-6 equipped a drive-through fast load lock system (I), a
preparation chamber (II), the main deposition chamber (III), and an analysis chamber (IV).
The Oxide-MBE setup utilized in the frame of this thesis allows for the deposition of magnetic
oxide heterostructures in conjunction with oxides or silicon substrates. Historically, mainly
metallic three-layer structures have been fabricated in this system since the 1980s in order
to explore novel electronic effects. In particular, in 1988 Fe/Cr/Fe structures showed an “en-