Synthesis Of Diamond Thin Films Research Articles

Review of advances in diamond thin film synthesis

From time immemorial, diamond attracted a special attention not only as a precious gemstone but also as an application material due to its unique and unsurpassed properties. Interest in diamond thin film research has enormously increased owing to the fact that most of the diamond properties could be utilized for various applications only when it is in the form of a thin film. At present, diamond thin films are able to serve in applications such as electro-mechanical, electro-chemical, bio-medical, bio-sensing, optical, electronic, and machining. Chemical vapour deposition (CVD) is the standalone technique used for diamond thin film synthesis. The mechanism of which typically involves addition of one carbon atom at a time from carbon containing activated gas phase to an initial template resulting in sp3 carbon atom network (diamond). Depending on the synthesis conditions, diamond thin film can constitute epitaxial, oriented, and polycrystalline (micron- and nano-sized) diamond grains. This article reviews important advances that have taken place in diamond thin film synthesis.

A Brief Review on theIn SituSynthesis of Boron-Doped Diamond Thin Films

Diamond thin films are well known for their unsurpassed physical and chemical properties. In the recent past, research interests in the synthesis of conductive diamond thin films, especially the boron-doped diamond (BDD) thin films, have risen up to cater to the requirements of electronic, biosensoric, and electrochemical applications. BDD thin films are obtained by substituting some of thesp3hybridized carbon atoms in the diamond lattice with boron atoms. Depending on diamond thin film synthesis conditions, boron doping routes, and further processing steps (if any), different types of BDD diamond thin films with application-specific properties can be obtained. This paper will review several important advances in the synthesis of boron-doped diamond thin films, especially those synthesized via gas phase manipulation.

Al-enhanced low temperature deposition of diamond thin films on hetero-substrates

Synthesis of diamond thin films on aluminum and aluminum-modified Si and steel substrates has been performed at 450 °C with 1%CH 4–99%H 2 gas mixture in a microwave plasma enhanced chemical vapor deposition (CVD) reactor. A diamond scratching pre-treatment of bulk Al substrate or Al-interlayered Si/steel substrates greatly enhances diamond nucleation, and the diamond films directly synthesized on Al substrate are well faceted, continuous and densely packed. The diamond films synthesized on conventional Fe–Cr and Fe–Cr–Ni type steels are generally of poor quality due to preferential formation of graphitic carbons catalyzed by the base metal iron. An Al thin film interlayer applied on those steel surfaces has markedly enhanced the nucleation and adhesion properties of diamond films, and a direct alloying addition of Al to these steel substrates also promotes the formation of continuous, dense and adherent diamond films.

A review of nucleation, growth and low temperature synthesis of diamond thin films

Diamond thin films have outstanding optical, electrical, mechanical and thermal properties, which make these attractive for applications in a variety of current and future systems. In particular, the wide band gap, optical transparency and unusually high thermal conductivity of diamond thin films make them an ideal semiconductor for applications in current and future electronics. However, synthesis of diamond thin films with adequate quality remains a challenging task. Synthesis of diamond at low temperatures is even more challenging because of the difficulties in the nucleation and growth steps involved in diamond thin film deposition on a variety of substrates. Among the several deposition techniques for synthesising diamond films, plasma enhanced chemical vapour deposition is the most promising technique because of its potential for low temperature synthesis. Consequently, the first part of this paper reviews the current state of the nucleation and growth of diamond during chemical vapour deposition. A uniform and high nucleation density is a prerequisite for getting a good quality diamond film with significant growth rate. Also, since the process conditions for nucleation and growth steps are different, attempts are made in this review to identify the important parameters responsible for enhancing the nucleation and growth rates of diamond film. Describing the indispensable need for low temperature growth of diamond film, the second part of the paper reviews the research on the growth of diamond thin films at low temperatures. In spite of the slower kinetics at lower deposition temperatures, an attempt is made to identify the key processing conditions, which enhance the low temperature growth process. In addition, the mechanisms of diamond nucleation and growth are discussed based on the observations from in situ characterisation techniques such as Fourier transform infrared reflection absorption spectroscopy, real time spectroscopic ellipsometry and molecular beam mass spectroscopy.

Low temperature synthesis of diamond thin films through graphite etching in a microwave hydrogen plasma

Low temperature synthesis of diamond thin films through graphite etching in a microwave hydrogen plasma

Diamond synthesis by high-gravity d.c. plasma cvd (hgcvd) with active control of the substrate temperature

In the first part of this paper, subatmospheric CVD methods for diamond thin film synthesis under normal gravity and other conditions are reviewed, following their increased capability for large-scale manufacturing. Emphasis is given to current problems and advances in moderate pressure d.c. plasma CVD operating under normal gravity and high-gravity. In the second part, an experimental technique aimed at solving the problem of temperature uniformity on the substrate surface at high gravity is presented. This technique improved temperature uniformity during diamond deposition at various gravity conditions and allowed a more accurate assessment of the influence of gravity on diamond growth and thin-film morphology.

High quality homoepitaxial diamond thin film synthesis with high growth rate by a two-step growth method

Abstract Homoepitaxial diamond films grown in the condition of CH 4 /H 2 ratio lower than 0.15% in a microwave-assisted plasma chemical vapor deposition system had excellent electrical and optical properties without any unepitaxial crystallites (UCs). Under such a low CH 4 concentration condition, however, the growth rate becomes too slow to obtain a useful thickness. In order to overcome this problem, we attempted a two-step growth method. In the first step the substrate surface was treated by homoepitaxial growth of diamond in the presence of 0.05% CH 4 in H 2 ; in the second step the CH 4 concentration was increased. By considering the origin of UCs with cross-sectional transmission electron microscope studies, it was found that this method is based on surface improvement of the initial substrate by means of ultra-low CH 4 concentration growth. This method was quite useful for obtaining high quality films, with high growth rate and reproducibility.

Evolution of the deposited carbon during diamond thin film synthesis evidenced by in-situ optical studies

Reactivity of silicon substrates in hydrogen and methane gaseous mixtures has been studied by means of in-situ differential reflectivity measurements, in a hot filament assisted chemical vapour deposition reactor. Reflectivity changes have been related to substrate etching by atomic hydrogen, and to carbon deposition. Comparison of the results obtained on substrates scratched with diamond paste (on which diamond growth takes place) and on unscratched ones (no diamond growth) has allowed us to evidence reflectivity changes specific to the diamond formation.

Synthesis of Diamond Thin Films from Graphite by Gaseous Reaction and Application for Microgravity Environment

Synthesis of Diamond Thin Films from Graphite by Gaseous Reaction and Application for Microgravity Environment

Plasma-assisted chemical vapour deposition in a tunable microwave cavity

We describe a microwave plasma-assisted chemical vapour deposition facility with some novel features including the ability to adjust the microwave cavity tuning during operation, thereby maximizing the overall device efficiency. The initial application of the facility was for diamond thin film synthesis. Microwave power, generated by a magnetron obtained from a commercial microwave oven, enters the cylindrical resonant cavity from the top face, which can be adjusted to position the maximum electric field at the desired location within the cavity; this tuning can be done while the equipment is running, allowing fine adjustment of the field distribution when the cavity is plasma-loaded. The microwave power activates the reactant gases, which are at low pressure inside a quartz bell jar specimen chamber, and the cavity base plate has a window through which the rear face of the hot substrate can be viewed, allowing pyrometric temperature measurement. A moveable sample holder allows control of the sample position in relation to the plasma ball. The system is stable and the deposition rate is about 1.25 mu m h-1.

In situ optical investigations of diamond thin film growth on molybdenum substrates

Abstract In situ optical measurements have been performed during synthesis of diamond thin films by hot filament assisted chemical vapour deposition on molybdenum substrates. Monochromatic measurements of reflectivity and elastic scattered light intensity have enabled us to follow in real time the evolution of the diamond particle size. Hence, growth kinetic domains have been inferred. Spectroscopic measurements of differential reflectivity have evidenced diamond absorption processes during the diamond crystal growth.

Synthesis of Diamond Thin Films on TC4 by Using a Scanning Linear Flame

Abstract A scanning linear flame is used to deposit diamond films over a large area, and with high quality and good continuity by employing appropriate cooling means for the substrate. It is found that the structure and morphology of the deposited films mainly depend on the substrate temperature, the ratio of 02 to C2H2 flow rate and the relative position of the substrate with respect to the flame. These factors affecting the structure and morphology of diamond films are interrelated. Moreover, the influences of surface pretreatments on nucleation and growth of diamond films are also studied. The experimental results show that the nucleation density of diamond films is enhanced by scratching the surface of the substrate with diamond grit and initially coating a mechanical pump oil layer. For the substrate surface etched with metallographic etching acid, the nucleation and growth of diamond films are very uniform. In addition, the adhesion between the film and substrate is enhanced. Nucleation is favored o...

Simple, safe, and economical microwave plasma-assisted chemical vapor deposition facility

A simple and economical microwave plasma-assisted chemical vapor deposition facility has been developed and used for synthesis of diamond thin films. The system is similar to those developed by others but includes several unique features that make it particularly economical and safe, yet capable of producing high quality diamond films. A 2.45-GHz magnetron from a commercial microwave oven is used as the microwave power source. A conventional mixture of 0.2% methane in hydrogen is ionized in a bell jar reaction chamber located within a simple microwave cavity. By using a small hydrogen reservoir adjacent to the gas supply, an empty hydrogen tank can be replaced without interrupting film synthesis or causing any drift in plasma characteristics. Hence films can be deposited continuously for arbitrarily long periods while storing only a 24-h supply of explosive gases. System interlocks provide safe start-up and shut-down and allow unsupervised operation. Here we describe the electrical, microwave, and mechanical aspects of the system, and summarize the performance of the facility as used to reproducibly synthesize high quality diamond thin films.

Synthesis of diamond thin films through a transformation of a catalytically produced diamond precursor phase

Amorphous carbon (a-C:H) films were formed on Cu substrates using a carbide-forming transition metal (Mo, Ta or W) as a catalyst with hot-filament chemical vapour deposition (CVD). This amorphous carbon was transformed into diamond in less than one minute when heated at 1273 K with the hot filaments in a H 2-0.3%CH 4 atmosphere. During the heating etching and transformation took place simultaneously causing a thinning of the film. After the transformation, the film became transparent and insulating. Scanning electron micrographs of the precursor film and the film after the transformation were taken. Raman spectra of the precursor phase was similar to the reported spectra of a-C:H. Raman spectra of the transformed film, however, showed a distinct diamond peak at a wavenumber of 1331±2 cm −1 (FWHM≤10 cm −1). Continuous diamond films with a thickness of less than 1 μm were also grown using the same catalysts in approximately 4.5 h. It was proposed that precursor diamond particles formed at the catalytic surface-Cu boundary and diffused to the Cu surface where they were exposed to atomic hydrogen and then transformed into diamond.

Synthesis of Diamond Thin Films by DC Plasma Using organic Compounds

physica status solidi (a)Volume 128, Issue 1 p. K19-K22 Short Note Synthesis of Diamond Thin Films by DC Plasma Using organic Compounds Wanlu Wang, Wanlu Wang Physics Department, Lanzhou University Search for more papers by this authorKejun Liao, Kejun Liao Physics Department, Lanzhou University Search for more papers by this authorJinying Gao, Jinying Gao Physics Department, Lanzhou University Search for more papers by this author Wanlu Wang, Wanlu Wang Physics Department, Lanzhou University Search for more papers by this authorKejun Liao, Kejun Liao Physics Department, Lanzhou University Search for more papers by this authorJinying Gao, Jinying Gao Physics Department, Lanzhou University Search for more papers by this author First published: 16 November 1991 https://doi.org/10.1002/pssa.2211280133 Lanzhou 730 001, Gansu, People's Republic of China. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume128, Issue116 November 1991Pages K19-K22 RelatedInformation

Diamond thin film synthesis by dc glow plasma CVD method

Diamond thin film synthesis by dc glow plasma CVD method

Synthesis of diamond thin films by hot-filament- assisted chemical vapour deposition

Diamond thin films were prepared by thermal decomposition of methane and hydrogen in the presence of a hot tungsten filament. The crystalline structure of the films was characterized by reflection high energy electron diffraction, scanning electron microscopy (SEM) and Raman spectroscopy. SEM morphologies and Raman spectra depend on experimental conditions. The influence of experimental conditions on the growth process is discussed by consideration of the surface properties of diamond. For particular experimental conditions, growth of amorphous carbon with atoms in sp 2 or sp 3 sites is evidenced.

Synthesis of Diamond Thin Films and Diamond Particles by Thermal CVD Using Organic Compounds

Synthesis of Diamond Thin Films and Diamond Particles by Thermal CVD Using Organic Compounds