The R2P2 system is a large multi-component UHV system (base pressure 1 x 10^-10 mbar) allowing sample transfer within UHV between various preparation and characterisation chambers. Samples freshly prepared by MBE or PLD can subsequently be studied in situ. For STM operation, the R2P2 table can isolated from floor motion by pneumatic vibration suspension.

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LEED/Auger

Low Energy Electron Diffraction and Auger spectroscopy are used to determine the crystallographic order and the chemical composition of surfaces, respectively.

(2x2) reconstruction of a vacuum-annealed SrTiO₄ (001) surface at 69ev.

MBE System

Molecular beam epitaxy can be used for preparing well-defined clean homoepitaxial surfaces as well as heteroepitaxial systems. The MBA rig was used for e.g. homoepitaxial growth of isotropic pure Ge on, growth of Sn on InSb and Sn(111), etc.

Electrically-heated Knudsen-type cells with 1cm³ crucibles are used for sublimating the pure elements at temperatures up to 1400°C. In order to suppress impurity contamination, the entire MBE unit is in UHV surrounded by a liquid nitrogen shroud. The sample heater ensures homogenous heating up to 900°C.

RHEED

Reflected High-energy Diffraction is used for controlling the crystallographic structure of the epitaxial surface during the MBE growth process. Monitoring RHEED oscillations allows the contol of layer by layer growth.

Room T STM

This standard Omicron scanning tunneling microscope allows investigation of surface structures even if non-periodic. Occupied and unnoccupied electronic states near the Fermi edge can be probed by Scanning Tunneling spectroscopy with atomic spatial resolution.

A single tube scanner is used. A sample surface area of 1cm² is accessed by 2D coarse motion of the tip. In scanning mode an area of 350 x 350 nm is covered.

Sputter/Annealing

In this chamber surfaces can be prepared by Ar sputtering and annealing. The heater block reaches 900°C; ohmic sample heating is also possible. Temperatures above 250°C can be monitored by a pyrometer.

Laser

Pulsed laser deposition of RBCO (R=Y or rare earth): Absorption of a laser pulse (KrF laser, =248nm) leads to local explosion-like sublimation of the polycrystalline RBCO target. Forming a plasma plume, atoms, ions and particles are ejected from the surface and precipitate onto the heated substrate material such as SrTiO₃ or NdGaO₃, forming an epitaxial RBCO film.

PLD System

Pulsed laser deposition allows material transfer from a target onto a substrate keeping the stoichiometry to a greater extent. We employ PLD for high-temperature superconductor film growth: RBCO (R=Y or rare earth) films with thicknesses ranging from less than one unit cell to several hundred nanometers are grown onto substrates 5 x 10 mm in size.