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First results from our OMICRON Low-Temperature Surface Science Facility

In April 1997, the Low-Temperature Surface Science Facility from the Omicron NanoTechnology GmbH was delivered and commissioned at Experimentelle Physik I. It contains the LT-STM, which is capable of atomic resolution down below 5 Kelvin in 10 exp -11 mbar vacuum, and a high-resolution electron energy analyzer for photoemission. Both UHV chambers are connected by a cooled in-situ sample transfer.

We routinely obtain STM topographs with atomic resolution at 4.9 K from the Au(111)(23xsqrt(3)) reconstructed surface. The example shown in Figure 1 was measured with a gap voltage of +0.123 V at the Pt-Ir tip and a tunneling current of 0.13 nA. On the left side the typical "stripes" of the (23xsqrt(3)) reconstruction are visible, while the upper right area contains a stacking fault.

STM topograph

Figure 1


The performance of the 180 degrees hemispherical analyzer was tested with a silver foil at 10 K employing He I radiation (hv = 21.2 eV) and a pass energy of 0.7 eV. The Fermi-level onset as measured at 10 K gives a value of 10 meV and is practically entirely governed by the experimental energy resolution (see Figure 2).

performance of hemispherical analyzer

Figure 2