Electron Cyclotron Resonance Plasma Treatment Research Articles

Enhancement of Field Emission Properties of Carbon Nanotubes by ECR-Plasma Treatment

We report a significant improvement in electron field emission property of carbon nanotubes film by using an electron cyclotron resonance plasma treatment. Our research results reveal that plasma treatment can modify the surface morphology and enhance the field emission characteristics of carbon nanotubes. Raman spectra indicate that plasma treated CNTs sample has lesser defects. Before plasma treatment, low current density of 6.5 mA/cm2 at 3.0 V/μm and at a high turn-on field Eto of 2.4 V/μm was observed. ECR plasma treated CNTs showed a high current density of 20.0 mA/cm2 at 3.0 V/μm and at a low Eto of 1.6 V/μm. The calculated enhancement factors are 694 and 8721 for ECR-plasma untreated and treated carbon nanotubes, respectively. We found an increase in the enhancement factor and emission current after the ECR-plasma treatment. This may be attributed to creation of geometrical features through the removal of amorphous carbon and catalyst particles.

Effect of Oxidation Pressure on Controlling Octacalcium Phosphate Nucleation on Implant Titanium by ECR Plasma Oxidation

The surface oxide films were prepared by Electron Cyclotron Resonance (ECR) plasma oxidation on Ti substrates. Octacalcium phosphate (OCP) and dicalcium phosphate dihydrate (DCPD) peaks were formed after calcification by supersaturated calcium and phosphate solutions. Calcification ability was enhanced with increasing the oxidation time and the total pressure of ECR plasma treatment during oxidation. The results demonstrated that the calcium phosphate nucleation and the deposition can be controlled by various ECR plasma conditions.

Effect of ECR Plasma Treatment on Lithium Niobate Surface State*

The comparative scanning electron microscopy investigations of lithium niobate surface state before and after microwave plasma etching at the electron cyclotron resonance (ECR) conditions were carried out. The differences in the surface relief of +C and −C domains were explained by the effect of pyroelectric charges arising due to sample heating under etching. Subsurface layer was observed to charge after etching, domains of different polarity had charge of opposite sign. A number of structure defects in subsurface layers was found to decrease after ECR plasma treatment. This decrease can be associated with removing surface defect layer or disappearing of these defects due to their interaction with point defects created by plasma. *Paper originally presented at 10th European Meeting on Ferroelectricity, Cambridge, U.K., August 3–8, 2003.

Amorphous Si/insulator multilayers grown by vacuum deposition and electron cyclotron resonance plasma treatment

a-Si/insulator multilayers have been deposited on (0 0 1) Si by electron gun Si evaporation and periodic electron cyclotron resonance plasma oxidation or nitridation. Exposure to an O or N plasma resulted in the formation of a thin SiO 2 and SiN x layer whose thickness was self-limited and controlled by process parameters. For thin-layer (∼2 nm) Si/SiO 2 and Si/SiN x multilayers no visible photoluminescence (PL) was observed in most samples, although all exhibited weak “blue” PL. For the nitride multilayers, annealing at 750°C or 850°C induced visible PL that varied in peak energy with Si layer thickness. Depth profiling of a-Si caps on thin insulating layers revealed no detectable contamination for the SiN x layers, but substantial O contamination for the SiO 2 films.

Thermal desorption spectroscopic analysis for residual chlorine on Al–Si–Cu after Cl2 electron cyclotron resonance plasma etching

Thermal desorption spectroscopy is used to measure the amount of residual chlorine on Al–Si–Cu. The Al–Si–Cu surface is etched by Cl2 electron cyclotron resonance (ECR) plasma at substrate temperatures of 30 and −60 °C. The surfaces are then cleaned by one of the following methods: de-ionized water rinsing, H2 ECR plasma irradiation, or annealing in H2/N2 mixed gas. AlCl molecules, which may be responsible for aftercorrosion, are detected. Chlorine compounds, however, cannot be detected by conventional x-ray photoelectron spectroscopy or Auger electron spectroscopy. The low substrate temperature etching reduces the amount of residual chlorine. Moreover, the cleaning ability of the H2 ECR plasma treatment is no less than that of the de-ionized water rinse, and is superior to that of annealing in H2/N2 mixed gas.

In-situ process for AlGaAs compound semiconductor: Materials science and device fabrication

Processing of III-V compound semiconductor devices in an ultra-high vacuum or a controlled environment has received much attention during the past few years. Major advantages ofn- situ processing include the preservation of pristine material surface, improved device performance, and fabrication of novel devices. This paper reviews anin- situ process compatible with molecular beam epitaxy (MBE) with emphasis on the removal of oxides and surface contaminants from air-exposed GaAs and AIGaAs. We have characterized deep-etched and MBE regrown AIGaAs with the etching achieved using electron cyclotron resonance plasma treatment. A buried heterostructure vertical-cavity surface emitting laser diode fabricated using thisin- situ process is presented.

Removal of GaAs surface contaminants using H2 electron cyclotron resonance plasma treatment followed by Cl2 chemical etching

We report a novel dry process to remove the surface contaminants C, Si, and O from GaAs substrates. This method utilizes an electron cyclotron resonance hydrogen plasma to remove the native oxides, followed by a very brief Cl2 chemical etching of GaAs to further reduce C and Si residues, and a final vacuum anneal. Characterization by secondary ion-mass spectrometry (SIMS) typically reveals the removal of C, Si, and O at the overgrown/processed interface to the levels below the SIMS detection limit. The as-processed GaAs surface, a Ga-stabilized reconstructed (4×6), is atomically smooth, and is as clean as a surface of freshly grown GaAs epilayers.