Controlled Dosing of Molecular Vapors into Ultra-High Vacuum

In order to study the behavior of surface-bound molecules used in atomic layer deposition, it is necessary to be able to deliver finely controlled doses of chemical precursor vapors into an ultra-high vacuum (UHV) system containing a pristine sample surface. To enable controlled precursor dosing, an ballast chamber was constructed. The ballast chamber is capable of holding a precursor vapor at a specific pressure combined with a computer controlled valve that allows dosing of a fixed amount of gas into the UHV chamber. Here, the design and construction of the ballast chamber is discussed.