Characterization studies of diamond-like carbon films grown using a saddle-field fast-atom-beam source

In this article, we report results of an extensive characterization study involving scanning electron microscopy, spectroscopic ellipsometry (SE), photothermal deflection spectroscopy (PDS), x-ray photoelectron spectroscopy, x-ray Auger electron spectroscopy (XAES), current–voltage (I–V) measurements, hydrogen content evaluated from Fourier transform infrared spectroscopy and elastic recoil detection analysis, and also measurement of stress and hardness of diamond-like carbon (DLC) films. These films were grown using methane (CH4), acetylene (C2H2) gases, and benzene (C6H6) vapors into a saddle-field fast-atom-beam (FAB) source. DLC films formed by the saddle-field FAB source technique exhibit extremely low residual stress (0.12–0.26 GPa) and high Knoop hardness (9–22 GPa) measured at 50 g load. The values of optical constants (n, k, e1, e2) evaluated from SE, characteristic energy of band tail (Urbach energy, E0) evaluated from PDS studies, sp2 percentage evaluated from XAES data, the density of states [N(EF)] derived from space-charge-limited conduction, and the hydrogen content are found to decrease, and the sp3/sp2 ratio evaluated are found to increase with the increase of carbon-to-hydrogen ratio in the hydrocarbon gases/vapors used for growing DLC films by this technique. The values of E0, N(EF), hydrogen content, and sp3/sp2 ratio of these DLC films are found to be in the range of 180–280 meV, 1–6×1017 eV−1 cm−3, 3–8 at. % and 5.2–12.3, respectively, which are lower than the values of E0 (300–500 meV), N(EF) (∼1018 eV−1 cm−3), and hydrogen content (15–40 at. %) and higher than sp3/sp2 ratio (1.3–2.5) of DLC films grown by the more conventional rf self-bias technique reported in the literature.In this article, we report results of an extensive characterization study involving scanning electron microscopy, spectroscopic ellipsometry (SE), photothermal deflection spectroscopy (PDS), x-ray photoelectron spectroscopy, x-ray Auger electron spectroscopy (XAES), current–voltage (I–V) measurements, hydrogen content evaluated from Fourier transform infrared spectroscopy and elastic recoil detection analysis, and also measurement of stress and hardness of diamond-like carbon (DLC) films. These films were grown using methane (CH4), acetylene (C2H2) gases, and benzene (C6H6) vapors into a saddle-field fast-atom-beam (FAB) source. DLC films formed by the saddle-field FAB source technique exhibit extremely low residual stress (0.12–0.26 GPa) and high Knoop hardness (9–22 GPa) measured at 50 g load. The values of optical constants (n, k, e1, e2) evaluated from SE, characteristic energy of band tail (Urbach energy, E0) evaluated from PDS studies, sp2 percentage evaluated from XAES data, the density of states [...

[1]  Jaipal,et al.  Study of hydrogen in DLC film by ERDA with 58Ni ions , 1995 .

[2]  N. Savvides.  Fourfold to threefold transition in diamondlike amorphous carbon films: A study of optical and electrical properties , 1985 .

[3]  J. K. Walters,et al.  The atomic-scale structure of amorphous hydrogenated carbon , 1995 .

[4]  Demichelis,et al.  pi bands and gap states from optical absorption and electron-spin-resonance studies on amorphous carbon and amorphous hydrogenated carbon films. , 1991, Physical review. B, Condensed matter.

[5]  O. Matsumoto,et al.  Effect of dilution gases in methane on the deposition of diamond-like carbon in a microwave discharge III: Effect of rare gases , 1990 .

[6]  K. Geib,et al.  The C KLL first‐derivative x‐ray photoelectron spectroscopy spectra as a fingerprint of the carbon state and the characterization of diamondlike carbon films , 1987 .

[7]  A. Bubenzer,et al.  Hard carbon coatings with low optical absorption , 1983 .

[8]  J. Franks.  Preparation and properties of diamondlike carbon films , 1989 .

[9]  K. Geib,et al.  Comparison of the CKLL first-derivative auger spectra from XPS and AES using diamond, graphite, SiC and diamond-like-carbon films , 1987 .

[10]  W. Howells,et al.  A spectroscopic study of the structure of amorphous hydrogenated carbon , 1995 .

[11]  H. Okamoto,et al.  Blue light emission from a-C:H by thin film electroluminescence structure cell , 1989 .

[12]  R. E. Sah,et al.  Amorphous, Hydrogenated Carbon Films and Related Materials: Plasma Deposition and Film Properties , 1991 .

[13]  Datta,et al.  Optical-absorption edge and disorder effects in hydrogenated amorphous diamondlike carbon films. , 1989, Physical review. B, Condensed matter.

[14]  J. Angus,et al.  Diamond-Like Hydrocarbon and Carbon Films , 1991 .

[15]  Guanghua Chen,et al.  A study of electroluminescence in hydrogenated amorphous carbon films , 1989 .

[16]  Salvatore Scaglione,et al.  Evaluation of the sp2/sp3 ratio in amorphous carbon structure by XPS and XAES , 1991 .

[17]  A. Bubenzer,et al.  Bonding in hydrogenated hard carbon studied by optical spectroscopy , 1983 .

[18]  D. A. Shirley,et al.  X-ray photoemission studies of diamond, graphite, and glassy carbon valence bands , 1974 .

[19]  D. Mathine,et al.  Optical properties of "diamondlike" carbon films: An ellipsometric study , 1983 .

[20]  A. Grill,et al.  Stresses in diamond-like carbon films , 1993 .

[21]  H. Barshilia,et al.  On the determination of the sp3 to sp2 ratio in diamond-like carbon thin films , 1997 .

[22]  J. Sworakowski,et al.  Use of space‐charge‐limited current measurements to determine the properties of energetic distributions of bulk traps , 1980 .

[23]  A. Lettington.  Applications of diamond-like carbon thin films , 1993, Philosophical Transactions of the Royal Society of London. Series A: Physical and Engineering Sciences.

[24]  Jerome J. Cuomo,et al.  Infrared and Raman spectra of the silicon-hydrogen bonds in amorphous silicon prepared by glow discharge and sputtering , 1977 .

[25]  J. Robertson.  Electronic processes in hydrogenated amorphous carbon , 1996 .

[26]  Toshio Mori,et al.  Crystal structure of diamondlike carbon films prepared by ionized deposition from methane gas , 1984 .

[27]  L. Pichon,et al.  Investigation of microwave π transitions in cesium beam clocks operated with U‐shaped H plane waveguide cavities , 1995 .

[28]  G. Amaratunga,et al.  Use of space-charge-limited current to evaluate the electronic density of states in diamond-like carbon thin films , 1994 .

[29]  Jung,et al.  Preparation and properties of highly tetrahedral hydrogenated amorphous carbon. , 1996, Physical review. B, Condensed matter.

[30]  Hyman Joseph Levinstein,et al.  Thermal stresses and cracking resistance of dielectric films (SiN, Si3N4, and SiO2) on Si substrates , 1978 .

[31]  Sushil Kumar,et al.  Diamond‐like carbon films grown using a saddle field source , 1995 .

[32]  K. Mackenzie,et al.  The density of states in amorphous silicon determined by space-charge-limited current measurements , 1982 .

[33]  S. Zukotynski,et al.  Structural properties of a-C:H deposited using saddle-field glow-discharge decomposition of methane , 1995 .