Transparent conductors as solar energy materials: A panoramic review

We review the status of (Ti,Al)N based coatings obtained by various physical vapor deposition (PVD) techniques and compare their properties. PVD techniques based on sputtering and cathodic arc methods are widely used to deposit wear resistant (Ti,Al)N coatings. These techniques were further modified to improve the metal ionization rate and to eliminate macrodroplets from plasma streams. We summarize manufacture of target/cathode, substrate materials for deposition of coatings, deposition parameters, and the effect of deposition parameters on the physical and mechanical properties of (Ti,Al)N coatings. It is shown that (Ti,Al)N coatings by PVD enhance the wear, thermal, and oxidation resistance of a wide variety of tool materials. We discuss the wear resistant properties of (Ti,Al)N for various machining applications as compared with coatings such as TiN, Ti(C,N) and (Ti,Zr)N. High hardness (∼28–32 GPa), relatively low residual stress (∼5 GPa), superior oxidation resistance, high hot hardness, and low thermal conductivity make (Ti,Al)N coatings most desirable in dry machining and machining of abrasive alloys at high speeds. Multicomponent coatings based on different metallic and nonmetallic elements combine the benefit of individual components leading to a further refinement of coating properties. Alloying additions such as Cr and Y drastically improve the oxidation resistance, Zr and V improve the wear resistance, whereas, Si increases the hardness and resistance to chemical reactivity of the film. Addition of boron improves the abrasive wear behavior of Ti–Al based coatings due to the formation of TiB2 and BN phases depending on the deposition conditions. Hafnium based nitrides and carbides have potential for resistance to flank and crater wear. The presence of a large number of interfaces between individual layers of a multilayered structure results in a drastic increase in hardness and strength. (Ti,Al)N multilayer super lattice coatings with lattice periodicity of 5–10 nm allow creation of coatings with different properties than PVD deposited single layered thick coatings with columnar grain structure. A range of (Ti,Al)N based multilayers containing layers of (Ti,Al)CN, (Ti,Nb)N, TiN, AlN/TiN, CrN, Mo and WC are also reviewed. It is now possible to design new wear resistant or functional coatings based on a multilayer or a multicomponent system to meet the demanding applications of advanced materials.

Single layer and multilayer wear resistant coatings of (Ti,Al)N: a review

Structure and properties of TiN coatings

A simple model for the formation of compressive stress in thin films by ion bombardment

This paper revies the preparation and properties of hard forms of amorphous carbon and hydrogenated amorphous carbon, often known as diamond-like carbon. Properties such as the hydrogen content, sp 3 content, optical gap, refractive index, hardness, elastic modulus and friction and their dependence on the deposition conditions are described. Models of the electronic structure and mechanical properties are used to relate the physical properties to the atomic structure.

Properties of diamond-like carbon

Low‐energy bombardment by argon and oxygen ions has been used in the deposition of thin dielectric films of ZrO2. The film packing density has been improved from 0.83 to unity with a corresponding increase in the refractive index from 1.84 to 2.19. The highest stable refractive index measured was 2.23 for oxygen ion‐assisted deposition of ZrO2 on a substrate heated to 300 °C. Ion bombardment during condensation of evaporated ZrO2 on a room temperature substrate results in crystallization into the cubic phase which is consistent with previous studies of ion impact crystallization by thermal‐spike processes. At elevated substrate temperatures the monoclinic phase is also present.

Modification of the optical and structural properties of dielectric ZrO2 films by ion‐assisted deposition

Mixed thin films of TiO2 and SiO2 were produced by coevaporation from separate electron‐beam sources and simultaneous bombardment of the growing film with oxygen ions. The optical properties of the films were determined during growth by in situ ellipsometry and the surface composition of the deposited films studied by in situ ion scattering spectroscopy, ex situ x‐ray photoelectron spectroscopy, and energy filtered electron diffraction. The correlation between the optical and surface characterization is presented. There is evidence of local variations in the relative concentrations of TiO2 and SiO2. The position of the Si 2p binding energy depends on the TiO2 content in the film, indicating the possible formation of an intimate mixture.

https://espace.library.uq.edu.au/view/UQ:259794/UQ259794_OA.pdf

Ion-assisted deposition of mixed Tio2-Sio2 films

A filtered arc deposition process was used in the reactive deposition of macroparticle-free TiO 2 , TiN, and TiC films. The TiO 2 films were reactively deposited by arc evaporation of titanium in an oxygen atmosphere. The films deposited onto glass substrates heated to 350 °C had a rutile structure and a refractive index n 6.33 of 2.735 and extinction coefficient k 6.33 of 0.07. Films of TiN and TiC were prepared by reactive evaporation in nitrogen and methane respectively. The lattice parameters and preferred orientations of the deposited films were measured as a function of negative substrate bias. The films were characterized by microhardness measurements, X-ray photoelectron spectroscopy and X-ray diffraction.

Deposition of TiN, TiC, and TiO2 films by filtered arc evaporation

Titanium nitride films were deposited on steel and silicon substrates using a filtered arc evaporation process. The microhardness, crystallite size, residual stress, adhesion, surface roughness and crystallographic orientation of the films were studied as a function of substrate bias over the range 0 to -400 V. The mechanical and structural properties were found to depend upon the degree of substrate bias. The spectral reflectance in the region between 250 and 2500 nm was measured and compared with Kr + ion-assisted deposited TiN films. In addition, the electrical resistivity and the superconducting transition temperature of the filtered arc deposited TiN films were measured to be 20 μΩ cm and 4.3 K respectively.

R.P. Netterfield

Papers

Modification of the optical and structural properties of dielectric ZrO2 films by ion‐assisted deposition

Ion-assisted deposition of mixed Tio2-Sio2 films

Deposition of TiN, TiC, and TiO2 films by filtered arc evaporation

The properties of TiN films deposited by filtered arc evaporation

Ion-beam-deposited films produced by filtered arcevaporation