Experimental set-up for the cluster deposition experiment

Metal atoms (Al, Co, Cu, Ti,...) are sputtered in a gas discharge using a high pressure magnetron cathode. The typical pressure in the liquid nitrogen (LN2) cooled aggregation tube is about 0.1 to 1mbar. The sputtered atoms are decelerated by collisions with the rare gas and aggregate to clusters. The gas stream carries the clusters through two apertures into the deposition chamber with a typical pressure of  5x10-5mbar. The diameter of the first aperture is variable in order to adjust the pressure in the aggregation tube. A large part of the clusters is ionized due to efficient charge transfer processes in the sputter discharge. With an ion optics the charged clusters (c) are separated from the neutral beam (n) and either part of the cluster beam can be blocked by a movable diaphragm. Ionized clusters can be accelerated onto the substrate holder which can be floated up to 30kV. 
The deposition rate is measured by a quartz microbalance and reaches up to 1nm/s. The cluster size, measured by a time of flight mass spectrometer (TOF), depends on different process parameters as pressure in the aggregetion tube, discharge power, helium to argon ratio, etc. Rapid transfer to a X-ray photoelectron spectrometer (XPS) operating under UHV conditions allows in situ chemical surface analysis.