Gas-surface reactions relevant to indium nitride thin-film deposition on silicon and titanium dioxide substrates

The interaction of the atomic nitrogen and indium precursors with the surfaces of silicon and titanium dioxide (TiO2) is discussed in this dissertation in two parts. Part I includes the computational results of interfacial reactions on the reconstructed Si(100)-2 x 1 surface, which is the key crystal surface of silicon applied in most microelectronic device fabrication. Previously acquired experimental data on the reactions of several N-containing precursors on the Si(100)-2 x 1 surface investigated with X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), high-resolution electron energy loss spectroscopy (HREELS) and Auger electron spectroscopy (AES) in our group have been computationally simulated to elucidate their adsorption and decomposition mechanisms. Part II covers both experimental and computational results of indium nitride (InN) deposition by low-pressure organometallic chemical vapor deposition (OMCVD) and the reactions of the employed precursors, hydrazoic acid (HN3) and trimethyl indium (In(CH3)3), on TiO2 nanoparticle films.;In Part I, the desorption and decomposition of the N-containing molecules, cyanogen (C2N2), hydrazine (N2H4) and HN3 on the reconstructed Si(100)-2 x 1 surface are presented in Chapters 3, 4 and 5, respectively. A hybrid Hartree-Fock/density functional theory (HF/DFT) and effective core potential (ECP) basis set, LanL2DZ, are utilized with single (Si9H12) and double (Si15 H16) dimer surface models in the cluster calculations. Most of these cluster model results are confirmed with slab model calculations based on the DFT method with the exchange-correlation function treated by the generalized gradient approximation (GGA) and plane-wave basis set using pseudopotential functions. Comprehensive potential energy surfaces (PES) constructed with the computed adsorption energies of the optimized local minima and transition states can well rationalize the observations of XPS, UPS and AES from the surface annealing and photodissociation experiments. In addition, the computed vibrational frequencies of the adspecies agree well with the HREEL spectra measured in the experiments. The across-dimer reactions and adsorbate effects are also explicitly examined in these C2N2, N2 H4 and HN3/Si(100)-2 x 1 systems.;In Part II, the interfacial reactions of HN3 and In(CH 3)3 on TiO2 nanoparticle films have been experimentally studied by Fourier transform infrared (FTIR) spectroscopy, monitoring the effects of dosage, UV irradiation and surface heating; these results have been computationally modeled with first-principles calculations for the adsorption energies, vibrational frequencies of adspecies and potential energy surfaces of the adsorption, desorption and decomposition processes involving the individual precursors (Chapter 7). Effort has been made to elucidate the mechanisms for the formation of atomic nitrogen and indium from the decomposition of HN 3 and In(CH3)3 independently on the TiO2 surface as well as for the formation of InN from the reaction of HN 3 and In(CH3)3 co-adsorbed on the surface. In Chapter 8, the deposition of InN films by low-pressure OMCVD with HN 3 and In(CH3)3 has been discussed. The deposited films have been characterized by X-ray powder diffractometry (XRD) for their composition, analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) for their surface morphology, and detected by UV/visible spectroscopy for their photochemical properties. In addition, the possible adsorption configurations, energies and system's band gap for one monolayer InN adsorbed on the TiO2 surface have also been predicted computationally.