Effect of substrate pregrowth treatments on characteristics of low-temperature diamondlike carbon films prepared by very
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Alexander Nikolaivech Andronov Physical Electronics Department, Saint Petersburg State Technical University, Russian Federation Ministry of Education, 194251 Saint Petersburg, Russia
Andrey Kosarev and Igor Makarenko A.F. Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 Saint Petersburg, Russia (Received 22 January 2001; accepted 27 November 2001)
Diamondlike carbon (DLC) films were grown on Si and ceramic substrates by very-high-frequency chemical vapor deposition at temperature of approximately 250 °C. Thin metal coatings from Ti, Ni, Pt, and Cu were deposited on the substrates before DLC film deposition. The impact of the pregrowth treatments of the substrates on surface morphology and emission properties of the grown DLC films was studied. The films deposited on ceramic substrates pretreated by Ti, Ni, and Pt coatings, with grainlike structures, demonstrated good emission currents and low threshold voltages among the deposited DLC films.
I. INTRODUCTION
In recent years amorphous carbon, natural diamond, and diamondlike carbon (DLC) films grown by chemical vapor deposition (CVD) have emerged as promising materials for cold cathodes.1–5 The electron field emission (FE) from such carbon-based materials has been widely studied as a future candidate for microelectronic applications, such as in the construction of DLC-based semiconductor p-n junction devices.5 The typical properties of such films, such as high hardness, low friction, chemical inertness, and optical transparency provide these films with advantages over other types of materials used for optical and electrical applications.6,7 The special characteristics of these films, such as wide band gap, high breakdown fields, and thermal conductivity, are unique and very useful in high-temperature and highpower electronics.8 Due to the polycrystalline structure of carbon-based films prepared by CVD, structural defects, different carbon phases, and impurities strongly affect their optical and electronic properties.9–11 The properties of these films depend strongly on deposition parameters such as pressure, substrate temperature, plasma power, and precursor gases. Since the nature of these dependencies is not completely understood,12 the optimum parameters for carbon films deposition are difficult to determine. J. Mater. Res., Vol. 17, No. 2, Feb 2002
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One approach to optimization is the theoretical modeling of deposition process, but this is quite unreliable because many of the involved parameters are unknown.12,13 The main object of the studies may be the method of varying one parameter at a time while keeping all other parameters constant, thus measuring the influence of each parameter separately. However, this approach ignores interactions between the parameters and may miss the real optimum parameters.14 In most prior investigations, the carbon films were deposited at high temperatures (>600 °C).15–17 The low-temperature thin film deposition is more compatible for a practical use
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