Monolayer thickness in atomic layer deposition

Simulation of growth dynamics for nearly epitaxial films

“…This depends, in turn, on the chemical nature of the particular precursor and its physical size compared to the dimensions of the lattice of active sites on the crystal surface (see Ref. [11]). Hence, it should be possible to influence the microstructure of an ALD-grown film by application of different types of precursors to the growth process, because these may have different arrangements on a given crystallographic plane.…”

“…The rate-limiting factor for growth of the individual crystal facets is then given by the saturation density of precursor on each crystal facet. This approach thus differs from most other thin-film or crystal-growth techniques in the sense that the growth rate is not dependent on the supply rate of precursor, nucleation rate or similar effects, but rather on the packing density of precursor [11]. The ALD technique makes use of sequential pulsing of two or more reactants, with application of vacuum or purging with inert gas between the precursor pulses to avoid gas-phase reactions [12,13].…”

Optimization of CdTe nanofilm formation by electrochemical atomic layer epitaxy (EC-ALE)

“…EC-ALE is the electrochemical analog of ALE [17][18][19] and ALD [20][21][22][23], all methods based on the use of surface limited reactions to form deposits with atomic layer control. The advantages of these methodologies are that they can be used to control deposition at the atomic level.…”

Atomic Layer Deposition on Porous Materials: Problems with Conventional Approaches to Catalyst and Fuel Cell Electrode Preparation

“…Although the adsorption step preferably involves the loss of a ligand and the formation of a chemical bond, physically adsorbed species may be acceptable for some ALD systems on flat surfaces, so long as the single-layer physisorbed species interacts with the surface more strongly than the precursor molecules interact with a condensed film [54]. The advantage to using a physisorbed species is that the coverage of adsorbed precursors will be higher, leading to a higher growth rate [54].…”

“…Although the adsorption step preferably involves the loss of a ligand and the formation of a chemical bond, physically adsorbed species may be acceptable for some ALD systems on flat surfaces, so long as the single-layer physisorbed species interacts with the surface more strongly than the precursor molecules interact with a condensed film [54]. The advantage to using a physisorbed species is that the coverage of adsorbed precursors will be higher, leading to a higher growth rate [54]. For example, Keuter et al accurately calculated an expected growth rate for ZrO 2 using tetrakis(ethylmethylamino)-zirconium as the precursor based strictly on the physical size of the molecule, and the calculated surface coverage based on that size [28].…”