Nanostructural, surface morphological evolution, and physical properties of sodium chloride-structure titanium nitride and titanium cerium nitride layers as a function of composition.

摘要

TiNx is presently used in a variety of hard wear-resistant, optical coating, and diffusion-barrier applications. However, processing requirements generally require that the layers be deposited at high deposition rates and low temperatures (Ts ≲ 350°C), resulting in substoichiometric layers with underdense kinetically-limited microstructures and rough surfaces. Given the industrial importance of TiNx it is surprising that little is known about the properties of this materials system. In this thesis, I present the results of a detailed study of the growth and fundamental properties of substoichiometric epitaxial TiNx(001) layers as a function of x across the entire single phase field, 0.67--1.0. In addition, I develop a new approach, utilizing both alloying and low energy, high flux ion irradiation to control grain size, shape, and texture during the growth of TiNx-based polycrystalline thin films.; In order to investigate microstructural evolution and the physical properties of TiNx as a function of the N vacancy concentration, I have grown single-crystal NaCl-structure delta-TiNx layers with x ranging from 0.67 to 1.00 on MgO(001) at 700°C by ultrahigh vacuum (UHV) reactive magnetron sputtering of Ti in mixed Ar/N2 discharges Microstructures, surface morphologies, and room-temperature resistivities vary dramatically with x. The longitudinal sound velocity v1, the surface acoustic wave velocities v100SAW and v110SAW , and the elastic constants c11 and c44 of TiN x(001) (0.67 ≤ x ≤ 1.0) layers have been determined as a function of x using picosecond ultrasonic pump/probe measurements.; I use a combination of alloying and low-energy ion irradiation during film growth to controllably manipulate the nanostructure of TiN-based layers. Ti0.8Ce0.2N films are grown on oxidized Si(001) at 350°C using UHV reactive magnetron sputter deposition in pure N2. The N+2 to metal ratio incident at the growing film is maintained constant at 15 while the ion energy EN+2 is varied from 14 to 45 eV. Films grown with EN+2 = 14 eV consist of equiaxed nanograins with an average size of 2.0 nm while layers deposited with EN+2 = 45 eV exhibit a 2-nm-wide nanocolumnar structure. In both cases, the films are dense, atomically smooth, and have strong 002 preferred orientation with low stress.