Atomic Layer Deposition (ALD)is used to fabricate ultrathin and conformal thin film structures for many semiconductor and thin film device applications. ALD uses sequential self-limiting surface reactions to achieve control of film growth in the monolayer or sub-monolayer thickness regime. ALD is receiving attention for its potential applications in advanced high-k gate oxides, capacitor dielectrics and copper diffusion barriers in advanced electronic devices. It is also of interest in any advanced application that benefits from control of film structure in the nanometer or sub-nanometer scale.