Wall Of Quartz Tube Research Articles

One-step route to iron oxide-filled carbon nanotubes and bucky-onions based on the pyrolysis of organometallic precursors

Iron and iron oxide-filled carbon nanotubes (CNT) have been produced by an one-step route based on the pyrolysis of ferrocene or a ferrocene-Fe 3(CO) 12 mixture in a poor oxygen-containing atmosphere, using the reactor quartz tube wall and porous Vycor glass (PVG) as substrate. XRD, TEM and HRTEM studies reveal the presence of CNTs, bucky-onions and carbon nanopolyhedra, filled with α-Fe, Fe 2O 3 and Fe 3O 4. The carbon formed inside the pores of PVG was extracted from the glassy matrix yielding thin and short CNTs or structures resembling carbon foam. The preparative method opens up new avenues for iron oxide filled-CNT and bucky-onions synthesis.

Remote and direct cleaning by use of microwave plasma source SLAN II: Comparative study

A 2.45 GHz slot antenna microwave plasma source with a quartz tube as plasma chamber (diameter 66 cm and length 42 cm) has been applied for the removal of organic lubricants from glass substrates in a remote plasma. Optionally, a remote cage separating the primary discharge directly at the quartz tube wall from the diffusion bulk plasma in the process chamber was used. The radial and axial distributions of the ion concentrations (double-Langmuir-probe) and the removal rates (gravimetric technique) for source versions with and without the remote cage were investigated. Typical process conditions are power of 4 kW, pressure of 2–5 Pa, oxygen flow of 100 sccm. Ion concentrations of 8 × 10 10 and 1.5 × 10 10cm −3 were measured for direct and remote plasma, respectively. The removal rates are 800 and 150 nm min −1, respectively. The remote cage allows the suppression of local heating of substrates by microwaves and a reduction of the removal rate variation along the source length (less than 20%).

Heating silicon dioxide at 950–1050 °C in the presence of an NH3+CF4 plasma

Very thin SiO2 films thermally grown on Si were annealed at a temperature of 950 or 1050 °C in the glow discharge of either an NH3 gas containing 4% CF4 or a pure NH3. From the chemical analysis of annealed films using Auger electron spectroscopy and x-ray photoelectron spectroscopy, it is found that annealing has resulted in the formation of silicon nitride layer on the SiO2 surface and in the incorporation of bonded nitrogen into the SiO2 layer. It is also demonstrated that the surface nitride layer is formed primarily by the deposition of silicon nitride resulting from the reaction of fragments of NH3 with the silicon atoms produced by the plasma etching of the quartz tube wall by atomic hydrogen and fluorine.

SiO 2 coating and plasma anodization of metals and semiconductors

Simple techniques for the SiO 2 coating and plasma anodization of semiconductors and metals are proposed. We used a quartz glass tube as a plasma reactor. The low pressure glow discharges were sustained by using an inductively coupled 1 kW 13.56 MHz r.f. generator. The SiO 2 was deposited onto the substrate on an Al 2O 3 boat located in the induction coil region of the tube because of the sputtering of the quartz tube wall in an r.f. electrodeless glow discharge. The maximum deposition rate on GaAs was 40 Å min -1. The deposited film showed interference colour and corrosion resistance. We also carried out plasma anodization in the same reactor without an external d.c. power supply. A d.c. flows between the two electrodes in an r.f. glow discharge through an external resistance because of the asymmetry in the discharge or the electrodes. We used this current for anodic oxidation. The maximum GaAs oxidation rate was 1000 Å min -1.