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The effect of impurities on the interface cohesion in multilayers in transition metal nitrides
Češka, Jakub ; Zelený, Martin (referee) ; Černý, Miroslav (advisor)
This work deals with the study of transtition metal nitride multilayers using first-principles calculations. Objects of this study are three particular systems AlN / TiN, AlN / VN and TiN / VN. Studied systems are in the B1 structure with an interface along the (001) plane. The main goal is to unravel the effect of impurity on cohesion in these multilayers. The impurity in question is a substitutional O atom replacing N in the lattice. Preferred positions of these substitutions are predicted for three different concentrations of substitution impurity. These predictions are based on the energy balance of substitutions in different positions. Resulting preferred positions within the multilayer may differ depending on the oxygen concentration. In most cases, the preferred position is at the interface between the two nitrides. For such systems with oxygen impurity in the preferred position a cleavage energy along several (001) planes is calculated. The effect of the impurity on the value of cleavage energy depends on its concentration. In the case of AlN / TiN multilayer, a suitable concentration of the impurity may increase the cleavage energy of the weakest link in multilayer compared to clean multilayer. In other cases the presence of impurity either causes a decrease in the cleavage energy or does not significantly affect its value.
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Electronic structure and mechanical properties of interfaces in solids
Češka, Jakub ; Šesták, Petr (referee) ; Černý, Miroslav (advisor)
In this work I focus on a theoretical study of the properties of transition metal nitrides (TiN, AlN and VN in the rock-salt structure). In addition to the nitrides themselves, I focus on the interface in systems of multilayers consisting of pairs of these nitrides. For nitrides, I predict the lattice parameter and cleavage energy using ab initio calculations. For the interface, the main goal is to predict the cleavage energy of the interface and to predict the influence that an atom substituted in one of layers on the interface has on the value of cleavage energy. According to the calculations performed, an oxygen atom substituted in the interface has a significant influence on the value of cleavage energy. The value of cleavage energy for the interface with an oxygen atom differs significantly from that for the pure interface. Whether there was a decrease or an increase depended on which of the layers at the interface the oxygen atom was substituted in.
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The effect of impurities on the interface cohesion in multilayers in transition metal nitrides
Češka, Jakub ; Zelený, Martin (referee) ; Černý, Miroslav (advisor)
This work deals with the study of transtition metal nitride multilayers using first-principles calculations. Objects of this study are three particular systems AlN / TiN, AlN / VN and TiN / VN. Studied systems are in the B1 structure with an interface along the (001) plane. The main goal is to unravel the effect of impurity on cohesion in these multilayers. The impurity in question is a substitutional O atom replacing N in the lattice. Preferred positions of these substitutions are predicted for three different concentrations of substitution impurity. These predictions are based on the energy balance of substitutions in different positions. Resulting preferred positions within the multilayer may differ depending on the oxygen concentration. In most cases, the preferred position is at the interface between the two nitrides. For such systems with oxygen impurity in the preferred position a cleavage energy along several (001) planes is calculated. The effect of the impurity on the value of cleavage energy depends on its concentration. In the case of AlN / TiN multilayer, a suitable concentration of the impurity may increase the cleavage energy of the weakest link in multilayer compared to clean multilayer. In other cases the presence of impurity either causes a decrease in the cleavage energy or does not significantly affect its value.
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Electronic structure and mechanical properties of interfaces in solids
Češka, Jakub ; Šesták, Petr (referee) ; Černý, Miroslav (advisor)
In this work I focus on a theoretical study of the properties of transition metal nitrides (TiN, AlN and VN in the rock-salt structure). In addition to the nitrides themselves, I focus on the interface in systems of multilayers consisting of pairs of these nitrides. For nitrides, I predict the lattice parameter and cleavage energy using ab initio calculations. For the interface, the main goal is to predict the cleavage energy of the interface and to predict the influence that an atom substituted in one of layers on the interface has on the value of cleavage energy. According to the calculations performed, an oxygen atom substituted in the interface has a significant influence on the value of cleavage energy. The value of cleavage energy for the interface with an oxygen atom differs significantly from that for the pure interface. Whether there was a decrease or an increase depended on which of the layers at the interface the oxygen atom was substituted in.
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