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SiO x containing diamond like carbon (DLC) films have been deposited on silicon and stainless steel substrates under varying influence of RF self bias (− 25 to − 225 V) using a capacitively coupled RF generated plasma of argon (Ar), methane (CH 4 ) and hexamethyl disiloxane (HMDSO) gases. The deposited coatings have been characterized by load depth sensing nano indentation, spectroscopic elliposometry, X-ray photoelectron spectroscopy, Fourier transform infra-red spectroscopy and Raman spectroscopy. Plasma has also been characterized by emissive probe and results indicate that impinging ion energy is mainly controlled by the self-bias values in this case. Characterization of deposited films indicate that sp 3 bonded carbon content in the films is increasing with the RF self bias values on the substrates. A clear improvement in the optical, mechanical properties of the deposited films is seen with the increasing magnitude of RF self-bias. It is seen that with increasing magnitude of bias values, C content increases continuously in these films at the expanse of Si and O content and they finally got close towards ideal diamond like character beyond − 150 V bias values. [ABSTRACT FROM AUTHOR]

Yttria stabilized zirconia thin films have been deposited by RF plasma enhanced MOCVD technique on silicon substrates at substrate temperature of 400 °C. Plasma of precursor vapors of (2,7,7-trimethyl-3,5-octanedionate) yttrium (known as Y(tod) 3 ), (2,7,7-trimethyl-3,5-octanedionate) zirconium (known as Zr(tod) 4 ), oxygen and argon gases is used for deposition. To the best of our knowledge, plasma assisted MOCVD of YSZ films using octanediaonate precursors have not been reported in the literature so far. The deposited films have been characterized by GIXRD, FTIR, XPS, FESEM, AFM, XANES, EXAFS, EDAX and spectroscopic ellipsometry. Thickness of the films has been measured by stylus profilometer while tribological property measurement has been done to study mechanical behavior of the coatings. Characterization by different techniques indicates that properties of the films are dependent on the yttria content as well as on the structure of the films. [ABSTRACT FROM AUTHOR]

Extended X-ray absorption fine structure (EXAFS) and atomic force microscopy (AFM) studies are carried out on yttrium oxide (Y 2 O 3 ) thin films deposited by radio frequency plasma assisted metalorganic chemical vapor deposition (MOCVD) process at different RF self-bias (−50 V to −175 V with a step of −25 V) on silicon substrates. A (2,2,6,6-tetramethyl-3,5-heptanedionate) yttrium (commonly known as Y(thd) 3 ) precursor is used in a plasma of argon and oxygen gases at a substrate temperature of 350 °C for deposition. To gain profound understanding about influence of RF self-bias on the properties of the deposited Y 2 O 3 thin films, the films are characterized by EXAFS and AFM measurements. From the EXAFS measurements it is observed that oxygen co-ordination is high for the film deposited at the lowest self bias (−50 V) which is due to presence of higher amount of hydroxyl group in the sample. Oxygen coordination however decrease to lower values for the films deposited at self bias of −75 V. Y O bond length decreases gradually with increase in self bias indicating reduction in hydroxyl content. However there is reduction in bond length for the film deposited at −100 V as compared to other films resulting from structural changes. The disorder factor obtained from EXAFS measurement increases for films deposited at voltages beyond −125 V due to degradation in crystallinity of the films caused by increased bombardment by incident ions. From AFM measurements, it is observed that the surface morphology of the films also change with self bias. The root mean square roughness value and the entropy factor are found to be low for films deposited at lower bias values and increase for films deposited at bias voltages above −100 V. [ABSTRACT FROM AUTHOR]

Highlights: [•] Yttrium oxide thin films are deposited by RF Plasma MOCVD Process using Y(thd)3 precursor. [•] Films are deposited under varying influence of RF self-bias on the substrates during deposition (−50V to −175V). [•] It is possible to deposit single phase cubic Y2O3 films at low substrate temperature. [•] RF bias on substrate controls the texture of deposited film. [•] To the best of our knowledge, so far there is no reported study on the effect of RF substrate bias on properties of films. [ABSTRACT FROM AUTHOR]

SiO x containing diamond-like carbon (DLC) films are deposited on the stainless steel 316 substrates by radio frequency (r.f.) plasma assisted chemical vapor deposition (PACVD) process using plasma of Argon, methane gases and Hexamethyl Disiloxane vapors. The sp 3 /sp 2 ratio of carbon bonding in the films is found to increase with increase in bias. Films deposited at low bias voltage (-25 V) show onset of film spallation and critical failure during scratch test at low progressive load and it has high friction coefficient. In contrast, film deposited at −100 V bias shows low coefficient of friction <0.05. Such a low friction coefficient is related to optimum fraction of sp 2 carbon bonding and a-C contents. [ABSTRACT FROM AUTHOR]

The investigations reported here describe the synthesis of carbon nanowalls (CNWs) by microwave electron-cyclotron resonance (ECR) plasma-assisted chemical vapour deposition (PACVD) process without an application of external bias to the substrate during growth. CNWs were grown on silicon (Si) substrates using hydrogen (H2)/methane (CH4) plasma at 650°C substrate temperature. Nickel (Ni) was used as a catalyst for the synthesis of CNWs. To the best of our knowledge, this is the first report that describes the bias-independent growth of CNWs using the ECR PACVD process. Formation of CNWs is confirmed by scanning electron microscopy and Raman spectroscopy. The discussion part also includes a possible growth mechanism for CNWs in terms of the role of surface plasmons. [ABSTRACT FROM PUBLISHER]

Boron carbide films are increasingly being investigated for their application in new generation neutron detectors. It is implemented as conversion layer for neutrons and emerging as a potential alternative to 3 He based detectors. This work reports synthesis of boron carbide (B x C) films from ortho-carborane (o-C 2 B 10 H 12 ) by radio frequency (RF) plasma enhanced chemical vapour deposition (PECVD) technique. Dependence of chemical composition, stoichiometry and total macroscopic cross section (Σ t ) has been studied as a function of self-bias on the substrate, varied in the range −75 V to −175 V. Films were characterized by 3D optical profilometry, X-ray photoelectron spectroscopy (XPS), proton elastic backscattering spectrometry (p-EBS), Fourier transform infra-red spectroscopy (FTIR) and Field Emission Scanning Electron Microscope (FESEM). Characterization results show noticeable change in the bulk as well as surface chemical composition, surface morphology and film stoichiometry with self-bias. Neutron transmission measurements exhibit increase in Σ t from 170.47 cm −1 for −75 V film to 273.38 cm −1 for −175 V film with self-bias. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) have been directly grown on Inconel 600 substrates by microwave plasma enhanced chemical vapor deposition without using any external catalyst. Grown CNTs were characterized by field emission scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, Raman spectroscopy and field emission measurements. Characterization results show that field emission current density increases from 200 μA/cm 2 at ∼5.5 V/μm to 14.5 mA/cm 2 at ∼1.6 V/μA when substrate is heat-treated and incident microwave is attenuated before reaching it. Detailed characterization reveals that heat-treatment results in migration of Cr and Fe oxides towards the top surface which completely changes substrate morphology also. Microwave attenuation reduces reflection of microwaves from the substrate and increases residence time of the precursor over the substrate promoting high density growth of CNTs. The combination of these two process parameters resulted in growth of long, dense CNTs with bamboo-like defects that contributes to enhanced current density at lower applied field. [ABSTRACT FROM AUTHOR]