Publication

Quantum chemical study of the initial surface reactions of HfO2 atomic layer deposition on the hydroxylated GaAs(001)-4×2 surface

Wei Chen, Min Xu
2006
Article
Résumé

Initial surface reaction mechanism for atomic layer deposition of HfO2 on the hydroxylated GaAs(001)-4x2 surface using HfCl4 and H2O as precursors is investigated using hybrid density functional theory. The reaction between HfCl4 and H2O with the hydroxylated GaAs(001)-4x2 surface consists of two half-reactions: (1) HfCl4 with GaAs-OH sites and (2) H2O with Hf-Cl sites. The two half-reactions proceed through the formation of stable chemisorbed states, resulting in high activation barriers of 17.1 and 17.6 kcal/mol for HCl formation, respectively. Additional energies are also needed to desorb the respective physisorbed states HCl from the substrate surfaces.

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Concepts associés (32)
Réaction chimique
Une réaction chimique est une transformation de la matière au cours de laquelle les espèces chimiques qui constituent la matière sont modifiées. Les espèces qui sont consommées sont appelées réactifs ; les espèces formées au cours de la réaction sont appelées produits. Depuis les travaux de Lavoisier (1777), les scientifiques savent que la réaction chimique se fait sans variation mesurable de la masse : , qui traduit la conservation de la masse. thumb|La réaction aluminothermique est une oxydo-réduction spectaculaire.
Reaction rate
The reaction rate or rate of reaction is the speed at which a chemical reaction takes place, defined as proportional to the increase in the concentration of a product per unit time and to the decrease in the concentration of a reactant per unit time. Reaction rates can vary dramatically. For example, the oxidative rusting of iron under Earth's atmosphere is a slow reaction that can take many years, but the combustion of cellulose in a fire is a reaction that takes place in fractions of a second.
Rate equation
In chemistry, the rate law or rate equation for a chemical reaction is a mathematical equation that links the rate of forward reaction with the concentrations or pressures of the reactants and constant parameters (normally rate coefficients and partial reaction orders). For many reactions, the initial rate is given by a power law such as where [\mathrm{A}] and [\mathrm{B}] express the concentration of the species \mathrm{A} and \mathrm{B}, usually in moles per liter (molarity, M).
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