Mechanistic Investigation on Thermal Atomic Layer Deposition of Group 13 Oxides

Abstract

Atomic layer deposition (ALD), based on selflimiting surface reactions, has been proven as a superior deposition method for synthesis of nanoscale thin films. In the field of oxide ALD, alumina (Al 2 O 3 ) is the most widely and thoroughly studied, prominently through using trimethylaluminum (TMA) with water (H 2 O). However, there is less information about other group 13 element (B, Ga, and In) oxides using analogous trimethyl precursors. In this study, we investigate these precursors' detailed adsorption and oxidation mechanisms during thermal ALD using density functional theory (DFT). The hydroxyl-terminated surface is transformed to a methyl-terminated surface after reacting with the trimethyl precursors. For such reaction, the reactivity of trimethylboron is significantly lower than other precursors. Meanwhile, using H 2 O, oxidation of the surface methyl is facile only for −Al−CH 3 , and stronger oxidants such as H 2 O 2 or O 3 are required for the oxidation reactions during ALD of B, Ga, and In oxides.

Experimental and Theoretical Insights into Transition-Metal (Mo, Fe) Codoping in a Bifunctional Nickel Phosphide Microsphere Catalyst for Enhanced Overall Water Splitting

“…All ab initio calculations were performed with the Vienna Ab initio Simulation Package (VASP 5.4.1). − The projector augmented wave method was employed along with the generalized gradient approximation based on the Perdew–Burke–Ernzerhof (PBE) functional using a plane-wave cutoff energy of 500 eV. − The lattice constants and internal atomic positions were fully optimized until the residual forces were below 0.04 eV/Å. To avoid interactions between the layers, the vacuum slab space of a unit cell in the z -direction was set as 15 Å.…”

Comparative Study on Indium Precursors for Plasma-Enhanced Atomic Layer Deposition of In2O3 and Application to High-Performance Field-Effect Transistors

“…However, When TMIn is generated from the spontaneous dissociation of DATI, it can easily adsorb on the substrate (Figure 1a). 51 As there is a chance that the DA ligand remains with the DATI precursor until its adsorption reaction, the reaction of the full DATI precursor on the surface was considered. In reaction 1, DATI is adsorbed on the substrate, and the methyl ligand of the precursor reacts with hydrogen on the surface to form product 1 with the byproduct methane removed.…”

“…Several possible reaction pathways for the adsorption of DADI and DATI are considered, as shown in Figure a,b. When TMIn is generated from the spontaneous dissociation of DATI, it can easily adsorb on the substrate (Figure a) . As there is a chance that the DA ligand remains with the DATI precursor until its adsorption reaction, the reaction of the full DATI precursor on the surface was considered.…”

Synthesis of High Surface Area—Group 13—Metal Oxides via Atomic Layer Deposition on Mesoporous Silica

“…2 Torr•s) enabled the complete exchange of methyl groups, yielding In 2 O 3 with linear growth per cycle (gpc). These findings can be rationalized by high activation barriers to remove the methyl group through water (E a (Ga-CH 3 ) = 151.0 and (In-CH 3 ) = 169.8 kJ/mol), calculated by Shong et al [59]. Insufficient ligand removal can be overcome by the usage of reactants with higher oxidation potential such as O 2 -plasma [47].…”