Pengaruh Rapat Arus Terhadap Ketebalan Dan Struktur Kristal Lapisan Nikel pada Tembaga

The effect of current density on thickness and crystal structures of the coatings in the electroplating of nickel on copper has been investigated. The electroplating of nickel was conducted at a voltage of 0.5 V for 10 minutes with varied current densities of 0.3 mA/cm2 ; 0.6 mA/cm2 ; 0.9 mA/cm2 ; and 1 mA/cm2 . The nickel coatings werw tested by thickness measurement and crystal structures determination. The experimental results showed that the thickness of the nickel coatings increased as the current density increased. The XRD characterization of the nickel coatings revealed the diffraction patterns for cubic structures with orientation of (111) and (200). As the current density increases, the crystal with (111) and (200) orientation tends to be formed more lagely. Key Words: electroplating, thickness, crystal structur

Antimony-doped graphene nanoplatelets

Heteroatom doping into the graphitic frameworks have been intensively studied for the development of metal-free electrocatalysts. However, the choice of heteroatoms is limited to non-metallic elements and heteroatom-doped graphitic materials do not satisfy commercial demands in terms of cost and stability. Here we realize doping semimetal antimony (Sb) at the edges of graphene nanoplatelets (GnPs) via a simple mechanochemical reaction between pristine graphite and solid Sb. The covalent bonding of the metalloid Sb with the graphitic carbon is visualized using atomic-resolution transmission electron microscopy. The Sb-doped GnPs display zero loss of electrocatalytic activity for oxygen reduction reaction even after 100,000 cycles. Density functional theory calculations indicate that the multiple oxidation states (Sb3+ and Sb5+) of Sb are responsible for the unusual electrochemical stability. Sb-doped GnPs may provide new insights and practical methods for designing stable carbon-based electrocatalystsclose0

Hole mobility in AlₓGa₁₋ₓSb grown by metalorganic chemical vapour deposition

The temperature dependence of the hole mobilities of AlₓGa₁₋ₓSb films in the regime 0≤x≤0.25 has been examined by Van der Pauw-Hall measurements. The films have been grown by metalorganic chemical vapor deposition on Si-GaAs substrates using TMA1, TMGa, and TMSb precursors. The mobility decreases sharply when a small amount of A1 in the range 0 100 K), the same effect was due to lattice phonon scattering. At 300 and 77 K, the alloy scattering is the most important mechanism in AlₓGa₁₋ₓSb ternaries, however the temperature dependence of alloy scattering is less pronounced as the temperature decreases.6 page(s

GaSb/AlGaSb compound semiconductors grown by MOCVD for optoelectronic applications

AlₓGa₁−ₓSb films in the regime 0 ≤ x ≤ 0.30 have been grown by metalorganic chemical vapor deposition on GaAs and GaSb substrates using TMAl, TMGa and TMSb precursors. We report the effects of growth conditions on the optical properties. Samples grown at temperatures of 540°C, 580°C and 600°C and a V/III ratio of 1 have been investigated. The AlₓGa₁−ₓSb layers grown at 580°C and 600°C with a V/III ratio of 1 and Al content in the range of 0.5% to 25% were found to exhibit excellent optical quality with a very high optical transmission at energies below the bandgap. The principle photoluminescence features observed are attributed to bound exciton and donor-acceptor transitions with FWHM comparable to the best values reported elsewhere.7 page(s

X-ray photoelectron spectroscopy of Alx Ga1-xSb grown by metalorganic chemical vapour deposition

The extent of oxidation and growth derived oxygen contamination for Al₀.₀₅Ga₀.₉₅Sb grown by metalorganic chemical vapour deposition (MOCVD) were systematically investigated by X-ray photoelectron spectroscopy (XPS) using a system with high-energy resolution. The Sb3d₅/₂ and O1s peaks are well resolved and the Ga3d peaks are also well resolved. As expected, all samples investigated show oxide layers (Al₂2O₃, Sb₂O₂ and Ga₂O₅) on their surfaces. In particular the percentage of aluminium-oxide was very high compared with a small percentage of AlSb. This indicates that the surface aluminium is very reactive to oxygen from the environment. Carbon content on the surface was also very high. Deeper into the layer, the carbon signal was below the detection limit of XPS and secondary ion mass spectroscopy (SIMS) indicating that the carbon was due to atmospheric exposure. The results indicate extremely low carbon content for Al₀.₀₅Ga₀.₉₅Sb epilayers grown using TMAl, TMGa and TMSb as metalorganic precursors in an MOCVD system.4 page(s

Electrical properties of Te-doped MOCVD grown GaSb Schottky diodes

Dimethyltelluride has been used as a dopant source for GaSb epilayers grown by atmospheric pressure MOCVD (Metalorganic Chemical Vapour Deposition). Schottky diodes were fabricated using Al barriers and Au-Ge-Ni as Ohmic contact. Doping densities of about 4.1x10¹⁸ cm⁻³ and barrier heights of 0.63 eV are found from C-V measurements, compared to 0.59 eV determined from room temperature I-V measurements. Room temperature ideality factors are around 1.3, while its variation with temperature demonstrates the role of electron tunnelling through the depletion barrier. The carrier concentration probed by C-V is confirmed by van der Pauw Hall measurements. The effect of thermal annealing on the diodes is also reported.4 page(s