Epitaxial growth in large-lattice-mismatch systems

Epitaxial growth in the TiN/Si and TiN/GaAs metal-semiconductor systems with a large lattice mismatch was investigated. The orientation relationships have been found to be 〈001〉TiN∥〈001〉Si for TiN growth on Si(001) and [001]TiN∥[110]GaAs and [11̄0]TiN∥[1̄10]GaAs for TiN growth on GaAs(001). The epitaxial growth is characterized by domain epitaxial orientation relationships with m lattice constants of epilayer matching with n of the substrate and with a small residual domain mismatch present in the epilayer. This residual mismatch is responsible for a coherent strain energy. The magnitude of compression of Ti—N bond in the first atomic layer, contributing to the chemical free energy during the initial stages of growth, is found to be a very important factor in determining the orientation relationship. This result was used to explain the differences in the orientation relationships between TiN/Si and TiN/GaAs systems. The various energy terms associated with the domain epitaxial growth are evaluated to illustrate that the domain epitaxial growth is energetically favorable compared to the lattice-mismatched epitaxial growth. The results of this analysis illustrate that the observed variations in the epitaxial growth are consistent with the minimum energy configurations associated with the domain epitaxial growth.