Deposition of diamond films on metal substrates

In this paper we report on the growth of polycrystalline diamond films on Mo, W, and Ni substrates using oxy-acetylene combustion flame technique. Effect of substrate temperature on the growth of diamond films has been studied in the temperature range 600–1100°C. The deposits and their surface morphology has been characterized by X-ray diffraction and scanning electron microscopy (SEM). A short duration pretreatment of Mo substrates by outer zone of the oxy-acetylene flame at lower substrate temperatures, results in the improvement of quality and adherence of the films. Growth of diamond as well as other intermediate compounds depending on the nature of substrates and interface layers is discussed. Paper presented at the poster session of MRSI AGM VI, Kharagpur, 1995     

Field-emission characteristics of chemical vapor deposition-diamond films

Discontinuous and continuous diamond films with different morphologies and qualities were deposited on n²⁺-type Si(100) substrates, using the hot-filament chemical vapor deposition (CVD) technique from CH₄–H₂ gas mixtures. The field-emission characteristics of these diamond films were investigated. The turn-on fields at a 0.01mA/cm² current density were recorded for all the tested CVD-diamond films. It was found that discontinuous diamond films showed a much lower turn-on field (1.2 V/μm) than continuous ones (20 V/μm). The effective working function of continuous diamond films was around 0.1 eV, while that for discontinuous diamond films is about 0.03 eV. O₂ plasma post-deposition sharpening of thick diamond films indicated that the geometrical-field enhancement, caused by the surface topographic changes, has no significant influence on the turn-on field.     

Preparation of high quality polycrystalline silicon thin films by aluminum-induced crystallization

High quality polycrystalline silicon (poly-Si) thin films without Si islands were prepared by using aluminum-induced crystallization on glass substrates. Al and amorphous silicon films were deposited by vacuum thermal evaporation and radio frequency magnetron sputtering, respectively. The samples were annealed at 500 °C for 7 h and then Al was removed by wet etching. Scanning electron microscopy shows that there are two layers in the thin films. After the upper layer was peeled off, the lower poly-Si thin film was found to be of high crystalline quality. It presented a Raman peak at 521 cm^− 1 with full width at a half maximum of 5.23 cm^− 1, which is similar to c-Si wafer.     

Effects of SiNx interlayer on characterisation of amorphous diamond-like carbon films

The magnetron sputtering amorphous diamond-like carbon film is successfully deposited by SiN_x interlayer approach. The scanning electron microscopy study reveals the creation of high uniform surface micrograph diamond-like carbon films with SiN_x interlayer. For comparison, diamond-like carbon films with different interlayers are also grown. The Raman spectra are analyzed in order to characterize the stressed induce peak shifts of the films. The interactions of C atom with Si(100) and SiN_x surface are studied by density functional theory simulation. The effects of interlayers on the films deposition and the considering deposition mechanism are discussed. It is suggested that the diamond-like carbon and SiN_x bilayer structure can help to render applications in protective coatings and high quality silicon on diamond related radiation tolerance devices.     

Characterization of carbon thin films prepared by the thermal decomposition of spin coated polyacrylonitrile layers containing metal acetates

Polyacrylonitrile (PAN) layers were cast from dimethyl-formamide solutions onto quartz substrates by spin coating and subsequently annealed at up to 1000 °C in N₂ atmosphere. Carbonization was catalyzed by nickel or cobalt added to the solution as acetate salts. The synthesized films were approx. 970 nm thick and were characterized by Raman and infrared spectroscopy as well as thermogravimetric and electrical conductance measurements. We discuss the effects of carbonization temperature and metal concentration on the morphology, composition and electrical properties of the formed carbon layer. Increasing the amount of catalyst and the pyrolysis temperature was beneficial for the process and resulted in carbonaceous films with a higher degree of structural order as evidenced by the decreasing Raman I_D/I_G ratio and the increasing electrical conductivity of the films. Cobalt is a better catalyst for PAN carbonization than nickel as far as the structure of the product film is concerned.     

Effect of triethanolamine and sodium dodecyl sulfate on the formation of CuInSe2 thin films by electrodeposition

In this paper, we describe the development of a bath comprising triethanolamine and sodium dodecyl sulfate for electrodeposition of CuInSe₂ thin films, by which long-term bath stability was found to be improved and near-stoichiometric CuInSe₂ films with smooth surface morphology were obtained. Scanning electron microscopy studies reveal a dramatic improvement of the crystalline quality of CuInSe₂ films with the addition of sodium dodecyl sulfate. X-ray diffraction results and Raman spectra confirm that the improvement of the film growth is attributed to the synergistic effect of triethanolamine and sodium dodecyl sulfate. The addition of anionic surfactant sodium dodecyl sulfate can significantly improve the adherence between the CuInSe₂ layer and the substrate.     

Influence of substrate temperature on phase formation in Al-Cr thin films

Thin films (of the order of nm) of Al-Cr alloys were prepared by successive depositions by an electron gun in a vacuum chamber. Three Al and two Cr layers, of thicknesses as to yield the final composition, were deposited on both hot (350 °C and 440 °C) and cold (70 °C and 108 °C) substrates and the phases formed were characterized in each case by X-ray diffraction and TEM observations, both in bright and in dark field conditions. The results show that on the hot substrates, Bragg peaks that do not correspond to any reported crystalline or quasi-crystalline phase appear. Both the samples on cold substrates and those heated afterwards showed an amorphous structure by X-ray diffractomery but TEM demonstrated the presence of tiny faulted crystallites, with the same Bragg reflections than those deposited on hot substrates. The results show that, for the composition range studied, a new phase not reported before appears and the substrate temperature only produces crystallite growth, not the formation of new phases. Received: 26 May 2000 / Reviewed and accepted: 31 May 2000