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EFFECT OF CATALYST LAYER THICKNESS ON GROWTH OF CVD DIAMOND Fig. 3. X-ray diffraction spectra of the diamond films for (a) sample A, (b) sample B, (c) sample C. Table 1. Results of the XRD studies of the diamond films grown at different catalyst layer thicknesses 261
FATEMEH SHAHSAVARI, MAHMOOD GHORANNEVISS, ZAHRA KHALAJ, MIRCEA V. DIUDEA CONCLUSIONS In this study, the effect of different thicknesses layer of the Au catalyst was investigated in HFCVD system. Different thicknesses of nano catalyst layers within the range of 21-62nm, has different effects on CVD diamond growth. XRD characterizations presented changes in diffraction peaks of crystalline diamond within changing the catalyst thickness layer. Optimized catalyst layer thickness found in sample B with the sharpest peak and small FWHM which indicates the higher quality of CVD diamonds. In sample C with the highest catalyst layer thickness, the quality of diamond films decreased and other non diamond structures appeared. EXPRIMENTAL SECTION A hot filament CVD system was used for deposition of nanocrystalline diamond in which the tungsten filament was 1.1mm in diameter and about 1.5 cm in length. P-type silicon wafers with [100] orientation were used as the substrates. The substrates were ultrasonically cleaned in acetone, ethanol and deionized water for 15 minutes in each step to remove organic contaminants. After pretreatment of Si substrates, to deposit different catalyst layers of gold [38], they were loaded in a DC magnetron sputtering system at 1.3 Pa (10 -2 Torr) in Ar with Au target. The thickness of the gold nano layer of each substrate was measured by DEKTAK3 surface profile measuring system. Then the substrates put into the stainless steel subholder below the hot filament wires. The distance between filament and substrates was 1.5 cm. The chamber was pumped down to the base pressure of 1.3 Pa with a rotary pump and after that reached to 2×10 -2 Pa (1.5 ×10 -4 Torr) with diffusion pump. In the first step, argon gas with flow ratio of 208 sccm was introduced into the chamber for etching the substrates with total pressure of 4 KPa (30 Torr) for 45 minutes. In the second step, nitrogen was introduced into the chamber as an etching gas with flow rate of 80 sccm. At this time, the filament was reached to about 1600°C. The working p ressure was kept in 667 Pa (5 Torr) and duration of time was 40 minutes. In the last step, for growing the nanocrystalline diamond, a mixture of precursor gases of methane and hydrogen were introduced into the chamber. Methane and hydrogen were introduced to the reaction chamber with a total flow rate of 150 sccm to keep the CH4/H2 ratio at 10%. The working pressure in this step was 4 KPa and nanocrystalline diamond was grown after only 75 minutes. During each step, the substrate temperature was controlled by the thermocouple and was kept on 600°С. The deposited films were characterized by scanning electron microcopy (SEM, XL30), X-ray diffraction spectroscopy (Cu Kα, λ=0.1541 nm), and DEKTAK3 version 2.13 at room temperature. 262
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CHEMIA 3/2011
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CORINA COSTESCU, LAURA CORPAŞ, NIC
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Studia Universitatis Babes-Bolyai C
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MONICA BAIA, MONICA SCARISOREANU, I
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STUDIA UBB CHEMIA, LVI, 3, 2011 (p.
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PREPARATION, CHARACTERIZATION AND S
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SPECTROSCOPIC EVIDENCE OF COLLAGEN
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CORNEL-VIOREL POP, TRAIAN ŞTEFAN,
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VITALY ERUKHIMOVITCH, IGOR MUKMANOV
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DUMITRU GEORGESCU, ZSOLT PAP, MONIC
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MAHDIEH AZARI, ALI IRANMANESH DEFIN
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MAHDIEH AZARI, ALI IRANMANESH V ( G
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MAHDIEH AZARI, ALI IRANMANESH Now,
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MAHDIEH AZARI, ALI IRANMANESH Let T
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MAHDIEH AZARI, ALI IRANMANESH Let G
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MAHDIEH AZARI, ALI IRANMANESH ACKNO
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CRISTINA GRUIAN, HEINZ-JÜRGEN STEI
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CYCLODEXTRINS AND SMALL UNILAMELLAR
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CYCLODEXTRINS AND SMALL UNILAMELLAR
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PROTEIN ADHESION TO BIOACTIVE MICRO
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LC/MS ANALYSIS OF STEROLIC COMPOUND
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LC/MS ANALYSIS OF STEROLIC COMPOUND
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INVESTIGATION OF THE EFFECTS OF DEG
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PM3 CONFORMATIONAL ANALYSIS OF THE
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MIHAELA POP, STEFAN TRAIAN, LIVIU D
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DIMITRI A. SVISTUNENKO, MARY ADELUS
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MILICA TODEA, TEODORA MARCU, MONICA
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EDINA DORDAI, DANA ALINA MĂGDAŞ,
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UV ABSORPTION PROPERTIES OF DOPED P
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UV ABSORPTION PROPERTIES OF DOPED P
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HASTI ATEFI, MAHMOOD GHORANNEVISS,
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LUCIANA UDRESCU, BOGDAN MARTA, MIHA
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ALI MADANSHEKAF, MARJAN MORADI wher
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ALI MADANSHEKAF, MARJAN MORADI and
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ALI MADANSHEKAF, MARJAN MORADI Agai
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ROZALIA VERES, CONSTANTIN CIUCE, VI
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EVALUATION OF FREE RADICAL CONCENTR
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ECCENTRIC CONNECTIVITY INDEX OF TOR
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