Plasma Source Gas Research Articles

Application of Electron Cyclotron Resonance Assisted Plasma in GaN Deposition

An electron cyclotron resonance assisted plasma with N2 being the plasma source gas was employed to deposit hexagonal GaN on (0001) surface of α-Al2O3 substrate. By special gas distributor, trimethgallium was introduced into reactant zone. A 10 × 10 mm uniform GaN film was gained with relatively low deposition temperature, 560°C, and high growth rate of 1.4 μm/h. A good crystal microstructure was confirmed by its spectrum with full width at half maximum of 15 arcmin.

Visible emission from Er-doped GaN grown by solid source molecular beam epitaxy

Visible light emission has been obtained from Er-doped GaN thin films. The GaN was grown by molecular beam epitaxy on sapphire substrates using solid sources (for Ga, Al, and Er) and a plasma gas source for N2. Above GaN band-gap photoexcitation resulted in strong green emission. The emission spectrum consists of two narrow green lines at 537 and 558 nm and a broad peak at light blue wavelengths (480–510 nm). The narrow lines have been identified as Er transitions from the H11/22 and S3/24 levels to the I15/24 ground state. The intensity of the 558 nm emission decreases with increasing temperature, while the intensity of the 537 nm line actually peaks at ∼300 K. This effect is explained based on the thermalization of electrons between the two closely spaced energy levels.

Preparation of SiC Thin Film Using Organosilicon by Remote Plasma CVD Method

AbstractAn organosilicon compound, hexamethyldisilane (HMDS) was incorporated for SiC thin film preparation by remote plasma enhanced CVD method. We investigated how plasma excited radicals react with source monomers using two kinds of gas mixtures. It was found that film component and formation mechanism depends on stronger on plasma gases. Using a mixture of nitrogen and hydrogen gases as plasma gas source, deposited films contained large amounts of nitrogen. When uing an argon and hydrogen mixture, deposited film was a SiC with large hydrogen contents. In this research, we found that hydrogen radicals are very active for decomposition of monomer source gas and this can be related to precursors for film deposition. When using a mixture of argon and hydrogen as plasma gas, the film deposition speed was influenced by substrate temperature. The estimated activation energy was larger than the case of using nitrogen and hydrogen gases. Different reaction mechanisms were observed for different plasma gas source

Optical and Structural Properties of Er3+-Doped GaN Grown by MBE

AbstractWe report the morphological and compositional characteristics of Er-doped GaN grown by MBE on Si(111) substrates and their effect on optical properties. The GaN was grown by molecular beam epitaxy using solid sources (for Ga and Er) and a plasma gas source for N2. The films emit by photoexcitation in the visible and near infrared wavelengths from the Er atomic levels. The morphology of the GaN:Er films was examined by AFM. Composition was determined by SIMS depth profiling that revealed a large Er concentration at 4.5 × 1021 atoms/cm3 accompanied by a high oxygen impurity concentration.

Graft polymerization of hydrophilic monomers onto textile fibers treated by glow discharge plasma

Graft polymerization of vinyl monomers was made onto some natural and synthetic textile fibers that were pretreated by glow discharge plasmas. Among the monomers investigated, 2-hydroxyethyl methacrylate (HEMA) produced the most improved grafting effects. Effects of plasma gas source, exposing time of glow discharge, grafting time, temperature, etc., on grafting were investigated. Postpolymerization in vacuum allowing oxygen shutoff was desirable for improved grafting yield. Air exposure of the plasma pretreated textile fabrics lead to decrease of grafting yield prominently because of the deactivation of radicals by oxidation. Grafting amount was dependent also on the nature of the substrate textile fibers, and cotton was, in general, more reactive. Breaking strength of yarns increased after graft polymerization of HEMA, while the strength decreased by etching of yarns by plasma treatments using nonpolymerizable gas species. Increase of the strength in the grafted yarn is attributed to binding effect of the grafted polymers as revealed from studies of morphology by scanning electron microscopy. © 1996 John Wiley & Sons, Inc.