Search query: low temperature diamond

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abstract: Diamond thin films represent a class of multi functional materials whose morphological, chemical, optical and electronic properties can be tailored on demand for specific applications. Nevertheless, this material's versatility inherently requires a high degree of control and understanding of the diamond growth technology. Here, especially, processes at low temperatures become important because of physical limitations regarding the intrinsic properties of typical target substrates (i.e. low melting temperature, high expansion coefficient, high thermal diffusion and chemical reactivity) and compatibility with standard semiconductor industrial technologies. However, low temperature diamond growth (LTDG) is still highly challenging, where novel phenomena are encountered that still remain to be understood. The present chapter focuses on low temperature diamond growth from technological and practical points of view. The LTDG process is divided in two strategies, which are based on i) the modification of the deposition systems and ii) the change of gas chemistry. The state of the art of each strategy and the fundamental growth processes that are involved are reviewed. Among the discussed diamond growth processes, microwave surface wave plasma in linear antenna configuration with oxygen containing gas mixtures is shown as the most promising process for LTDG over large areas with high optical and electronic grade materials. The growth phenomena observed in linear antenna microwave plasma provide a simple way to control nano and poly crystalline diamond character. A practical comparison between focused and linear antenna microwave plasma is presented on several key studies, which utilize LTDG on amorphous silicon, glass, germanium and optical elements used for IR spectroscopy.
author_names: T Izak

Oleg Babchenko

Stepan Potocky

Zdenek Remes

Halyna Kozak

Elisseos Verveniotis

Bohuslav Rezek

Alexander Kromka
title: CHAPTER 13:Low Temperature Diamond Growth
year: 2014

abstract: Recently, there is a great effort to increase the deposition area and decrease the process temperature for diamond growth which will enlarge its applications including use of temperature sensitive substrates. In this work, we report on the large area (20 x 30 cm2) and low temperature (250 degC) polycrystalline diamond growth by pulsed linear antenna microwave plasma system. The influence of substrate temperature varied from 250 to 680 degC, as controlled by the table heater and/or by microwave power, is studied. It was found that the growth rate, film morphology and diamond to non diamond phases (sp3/sp2 carbon bonds) are influenced by the growth temperature, as confirmed by SEM and Raman measurements. The surface chemistry and growth processes were studied in terms of activation energies (Ea) calculated from Arrhenius plots. The activation energies of growth processes were very low (1.7 and 7.8 kcal mol 1) indicating an energetically favourable growth process from the CO2CH4H2 gas mixture. In addition, from activation energies two different growth regimes were observed at low and high temperatures, indicating different growth mechanism.
author_names: T Izak

Oleg Babchenko

Marian Varga

Stepan Potocky

Alexander Kromka
title: Low temperature diamond growth by linear antenna plasma CVD over large area
year: 2012

abstract: Laser excited N and R fluorescence lines of heavily doped ruby have been studied up to 26 GPa at low temperatures. While the intensity of the R lines at ambient pressure significantly decreases with decreasing temperature, the intensity of N lines originating from exchange coupled Cr ion pairs is enhanced at low temperatures. The pressure induced wavelength shift of the N lines at 19 K is well fitted with an empirical formula similar to the equation for the R1 line, showing that the intense N line could be used as an alternative pressure scale at low temperatures. We also observe continuous increase in non hydrostaticity with increasing pressure at low temperatures when silicone oil and 4:1 mixture of methanol and ethanol are used as pressure media.
author_names: Hitoshi Yamaoka

Yumiko Zekko

Ignace Jarrige

Jung-Fu Lin

Nozomu Hiraoka

Hirofumi Ishii

K-D Tsuei

Jun'ichiro Mizuki
title: Ruby pressure scale in a low temperature diamond anvil cell
year: 2012

abstract: The deposition of low energy carbon atoms onto a low temperature diamond (111) surface is studied by molecular dynamics computer simulations. A Stillinger Weber potential [F. H. Stillinger and T. A. Weber, Phys. Rev. B 31, 5262 (1985) with a reparametrization derived from quantum mechanical energy calculations for small tetrahedral carbon clusters, is used to model the interatomic interactions. The penetration of 1 100 eV neutral carbon atoms into the diamond (111) surface at 100 K and the resultant surface atom rearrangements and induced film stress are studied. For intermediate energies (20 60 eV) the incident atom penetrates beneath the exposed (111) surface and significantly increases the lateral compressive stress in the diamond film. The emerging picture is that diamond films grow from below the exposed surface in a region of locally high stress and tetrahedral coordination.
author_names: Bernard A Pailthorpe
title: Molecular dynamics simulations of atomic processes at the low temperature diamond (111) surface
year: 1991

abstract: Thin diamond films were deposited on silicon, MgO, fused silica, and soda lime silica glass at low temperature (the lowest temperature ~365 degC) by microwave plasma enhanced chemical vapor deposition. The films were identified as diamond by Raman spectroscopy. A Raman peak shift of several wave numbers to either lower or higher wave numbers due to the strain of the film is also observed. The film deposited on glass is highly transparent. The fine faceted crystals in the film are shown in scanning electron microscope micrographs.
author_names: Yu-Chen Liou

Aharon Inspektor

Ronald A Weimer

Russell Messier
title: Low temperature diamond deposition by microwave plasma enhanced chemical vapor deposition
year: 1989

abstract: Preliminary studies have shown that diamond like carbon (DLC) coatings can be adherent on a range of substrate materials, resistant to wear and non toxic to cells in vitro. This has led to the question of the possible biomedical application of DLC coated materials, particularly in the field of implantation surgery. Assessment of the biocompatibility of implanted material requires two questions to be addressed: (1) is the implanted material toxic to cell growth, and (2) what is the nature of the cell DLC layer interaction? In this study we show, by the Kenacid Blue cytotoxicity test, that cells grown on DLC coated PCF membranes exhibit an initial increased attachment to the carbon substrate, and thereafter exhibit a normal growth rate over the 3 day test periods compared with cells grown on uncoated polystyrene. Scanning electron microscopy shows these cells possess characteristics typical of normal cell attachment and growth. Cells were grown on DLC coated PCF membranes to facilitate examination of the cell DLC coating interface by transmission electron microscopy. These results show that cells grown on both DLC coated and non coated membranes presented normal morphological characteristics of attachment and growth. These findings indicate that the DLC coating is non toxic in vitro and sustains normal cell growth.
author_names: T L Parker

K L Parker

I R McColl

David M Grant

John Vivian Wood
title: The biocompatibility of low temperature diamond like carbon films: a transmission electron microscopy, scanning electron microscopy and cytotoxicity study
year: 1994

abstract: Microwave plasma enhanced chemical vapor deposition has been used to grow diamond films at substrate temperatures down to 435 degC using CO2/CH4 gas mixtures. An Arrhenius plot of growth rate as a function of substrate temperature yields a value for the activation energy for the growth step of 28 kJ mol 1. This is lower than that measured previously for CH4/H2 systems and hints at a different gas surface chemistry when using CH4/CO2 plasmas. Molecular beam mass spectrometry has been used to measure simultaneously the concentrations of the dominant gas phase species present during growth, for a wide range of plasma gas mixtures (0% 80% CH4, balance CO2) The CHEMKIN computer package has also been used to simulate the experimental results in order to gain insight into the major reactions occurring within the microwave plasma. The calculated trends for all species agree well with the experimental observations. Using these data, the model for the gas phase chemistry can be reduced to only four overall reactions.
author_names: James R Petherbridge

Paul W May

S R J Pearce

Keith N Rosser

Michael N R Ashfold
title: Low temperature diamond growth using CO2/CH4 plasmas: Molecular beam mass spectrometry and computer simulation investigations
year: 2001

abstract: A new regime for plasma assisted chemical vapor deposition (CVD) of diamond is reported in which high quality diamond films can be deposited on silicon with relatively high ratios of methane in hydrogen mixtures and at significantly lower substrate temperatures than previously reported. The deposition was achieved in a microwave plasma discharge with a feed gas consisting of a mixture of only methane and hydrogen. The surface temperature of a molybdenum sample, when exposed to the same plasma environment, was measured at 500 degC with an infrared scanning camera. This substrate temperature is substantially lower than the 700 1000 degC range generally regarded as the optimal regime for CVD diamond growth. Analysis by Raman spectroscopy showed that films deposited with a 2% methane in hydrogen mixture produced a near graphite free diamond film at our reported low temperature regime, while deposition at 1000 degC resulted in films with a much higher graphitic content.
author_names: Wen L Hsu

D M Tung

Elke Fuchs

K F Mccarty

A Joshi

Rao R Nimmagadda
title: Low temperature diamond growth in a microwave discharge
year: 1989

abstract: Abstract The interaction of chlorine with CVD diamond surfaces has been studied using Auger and photoelectron spectroscopy techniques, with reference to the development of low temperature growth models for diamond using halogen based precursors. Chlorine is found to adsorb on the clean CVD surface with a sticking probability of ~0.001 at 300 K, although this can be enhanced by prehydrogenation of the surface and by raising the substrate temperature. Adsorbed chlorine desorbs from the surface over a wide temperature range below 500degC, and is also very efficiently etched away by atomic hydrogen. Chlorine has therefore little tendency to poison the growth surface, and thus is capable of acting as a catalyst for low temperature growth.
author_names: S Proffitt

Christopher H B Thompson

Aurora Gutierrez-Sosa

Nathan J Paris

Nagindar K Singh

Richard B Jackman

John S Foord
title: Understanding the chemistry of low temperature diamond growth: an investigation into the interaction of chlorine and atomic hydrogen at CVD diamond surfaces
year: 2000

abstract: Abstract Using magneto active plasma CVD, diamond films have been fabricated at 0.01 torr with a substrate temperature of about 400degC. From the viewpoint of increasing plasma density, a gas mixture,CH 3 OH/(H 2 +He) obtained by adding a helium to a usually used gas mixtureCH 3 OH/H 2 has been employed in this study. For a constant CH 3 OH concentration (30% microcrystalline diamond films of good quality can be obtained at a ratio ofHe/(H 2 +He) up to 50% and the growth rate increases with an increase in the ratio. WhenHe/(H 2 +He) is higher than 50% graphite appears in the film because of the heavy bombardment on the diamond surface by the accelerated helium species in the plasma at low pressure (0.01 torr)
author_names: Motokazu Yuasa

Osamu Arakaki

J S Ma

Akio Hiraki

Hiroshi Kawarada
title: Low temperature diamond film fabrication using magneto active plasma CVD
year: 1992