Wei-Long Liu

Effect of Fe metal on the growth of silicon oxide nanowires

Silicon oxide (SiO(subscript x)) nanowires are generally grown on Si substrate under the catalysis of Au in N2 atmosphere at elevated temperatures. Because the price of Au metal is quite high, Fe metal is then used to replace a part of Au for catalyzing the growth of SiO(subscript x) nanowires. The results show that the Fe film can be used as the diffusion barrier of Au. SiO(subscript x) nanowires are grown on Au/Fe/Si substrate at 1030℃. Under the catalysis of Fe/Au, the efficiency for the growth of SiO(subscript x) nanowires is promoted.

Synthesis of the CuInSe2 thin film for solar cells using the electrodeposition technique and Taguchi method

Abstract The Taguchi method was used to obtain the optimum electrodeposition parameters for the synthesis of the CuInSe 2 thin film for solar cells. The parameters consist of annealing temperature, current density, CuCl 2 concentration, FeCl 3 concentration, H 2 SeO 3 concentration, TEA amount, pH value, and deposition time. The experiments were carried out according to an L 18 (2 1 3 7 ) table. An X-ray diffractometer (XRD) and a scanning electron microscope (SEM) were respectively used to analyze the phases and observe the microstructure and the grain size of the CuInSe 2 film before and after annealing treatment. The results showed that the CuInSe 2 phase was deposited with a preferred plane (112) parallel to the substrate surface. The optimum parameters are as follows: current density, 7 mA/cm 2 ; CuCl 2 concentration, 10 mM; FeCl 3 concentration, 50 mM; H 2 SeO 3 concentration, 15 mM; TEA amount, 0 mL; pH value, 1.65; deposition time, 10 min; and annealing temperature, 500°C.

Kinetics of electroless Ni-Cu-P deposits on silicon in a basic hypophosphite-type bath

Abstract Electroless Ni-Cu-P deposits were deposited on the Si substrate in a basic hypophosphite-type plating bath. The effects of pH value and the metal source composition, Ni and Cu, in the plating bath on the kinetics of the Ni-Cu-P deposition were studied. The electroless Ni-Cu-P deposits were characterized by a scanning electron microscope, a transmission electron microscope, an energy dispersive X-ray spectroscope, and an X-ray diffractometer. The results showed that the pH value of the plating bath had no obvious effect on the morphology and composition of electroless Ni-Cu-P deposits. However, the composition of the metal source, Ni and Cu, in the plating bath had great effect on the kinetics of electroless Ni-Cu-P deposition.

Growth behavior of electroless copper on silicon substrate

Abstract The growth behavior containing deposit morphology, growth rate, activation energy, and growth mechanism of copper on silicon substrate, especially at the initial stage, in the electroless plating process was studied. Copper was deposited on the surface of the silicon substrate in an electroless plating bath containing formalin (CH2O 37vol%) as a reducing agent at a pH value of 12.5 and a temperature of 50-75°C. The copper deposit was characterized using a field emission scanning electron microscope and transmission electron microscope. The results showed that after the activation process, nanoscale Pd particles were distributed evenly on the surface of the silicon; in the deposition process, copper first nucleated at locations not only near the Pd particles but also between the Pd particles: the growth rate of electroless Cu ranged from 0.517 nm/s at 50°C to 1.929 nm/s at 75°C. The activation energy of electroless Cu on Si was 52.97 kJ/mol.

Growth Behavior of Ni–P Film on Fe/Si Substrate in an Acid Electroless Plating Bath

Ni-P film was electrolessly deposited on Fe/Si substrate in an acid plating bath containing nickel sulfate as the nickel source and sodium hypophosphite as a reducing agent. The Fe film in Fe/Si substrate was formed by electron-beam evaporation deposition. The Ni-P film was characterized by transmission electron microscopy. The results showed that the Ni-P film on Fe/Si substrate has a homogeneous and nanocrystalline structure in comparison with that on Si substrate, which has a columnar structure, and there are straight cracks in the Ni-P film when the pH value of the plating bath is relatively high due to the higher internal tensile stress. The plating rates of Ni-P film on Fe/Si substrate increase with increase in plating temperature and pH value, ranging from 0.22 to 5.27 nm/s for plating temperatures of 65-90°C and pH values of 4.2-5.0. The activation energies of Ni-P films on Fe/Si substrate were 99.58, 87.4, and 41.55 kJ/mol for pH values of 4.2, 4.6, and 5.0, respectively.

Tribological properties of electroless Ni-P-SiC composite coatings in rolling/sliding contact under boundary lubrication

Abstract Ni-P-SiC composite coatings were prepared under a given bath composition and operation parameters of electroless plating. The tribological properties of the Ni-P-SiC composite coatings after annealing at 400°C for 1 h were tested in rolling/sliding contact under boundary lubrication condition using a two-roller tribometer. The measurement contained friction coefficient, contact surface temperature, contact electrical resistance, and wear rate of the Ni-P-SiC composite coatings under various slide to roll ratios, loads, and rolling speeds. For the simultaneous examination of the effect of the chosen parameters on the tribological properties of the Ni-P-SiC composite coatings, an orthogonal regression experimental design method was used.

Interface Structure between Epitaxial NiSi2 and Si

The interface structure between the Si and NiSi2 epitaxially grown on the ((average)1 12) Si substrate was studied using high resolution transmission electron microscopy and computer image simulation. The results showed that the interface between Si and NiSi2 epitaxially grown on the ((average)1 12) Si substrate has six different types: Type A NiSi2 ((average)1 1 1)/((average)1 1 1) Si, type A NiSi2 (001)/(001) Si, type B NiSi2 (1 (average)1 (average)1)/(1 (average)1 1) Si, type B NiSi2 ((average)1 12)/(1 (average)1 2) Si, type B NiSi2 (2 (average)2 1)/(001) Si, and type B NiSi2 (1 (average)1(average)4)1 (1 (average)1 0) Si. And there are one or more different atomic structures for one type of interface.

Growth of graphite film over the tops of vertical carbon nanotubes using Ni/Ti/Si substrate

Abstract A substrate with Ni/Ti/Si structure was used to grow vertical carbon nanotubes (CNTs) with a graphite film over CNT tops by thermal chemical vapor deposition with CH4 gas as carbon source. The carbon nanotubes and the substrate were characterized by a field emission scanning electron microscope for the morphologies, a transmission electron microscope for the microstructures, a Raman spectrograph for the crystallinity, and an Auger electron spectrometer for the depth distribution of elements. The result shows that when the thickness ratio of Ni layer to Ti layer in substrate is about 1, a graphite film with relatively good quality can be formed on the CNT tops.