Corey John Collard

Optical emission reference data for the GEC reference cell

A complete set of optical emission data for the gaseous electronic conference reference cell (GEC) is presented for discharges at 75, 100, 150, and 200 V peak-to-peak and at pressures of 100, 250, 500, and 1000 mtorr. When the GEC project was initiated, these were the setpoints that were to be examined. This paper provides a set of data that can be used as a comparison for other diagnostics. The emission is compared to metastable data obtained from laser-induced fluorescence in helium and argon and computer generated data of the argon metastable data. There is good agreement between these three sets of data and the profiles found in this paper, which can be used as a consistency check for the capacitively coupled GEC reference cell. The data presented were collected with an automated scanning sensor, which gathers wedges of optical emission (Ar I 750.4 nm), at ten vertical heights parallel to the bottom electrode surface. The digitized data was converted to emissivity data as a function of radius using a Tikhonov regularization method.

RF plasma conditions for growth of carbon nanostructures

As the physical limits of silicon-based microelectronics are reached, a need for new materials is required in order to continually improve processor speed. Carbon nanotubes have been suggested as a material to fill in where silicon technology leaves off, due to their small dimensions and unique metallic and semiconductor properties. In order to better understand the conditions in which carbon nanostructures are formed, a detailed plasma analysis has been performed on a gaseous electronics conference (GEC) plasma chamber. This analysis includes plasma composition, rotational temperatures, and spatially resolved hydrogen actinometry during carbon nanostructure growth.

Spatially resolved analysis of carbon-based plasmas in an ICP system

Summary form only given, as follows. Summary form only given. We present experimental results on the spatially resolved analysis of carbon-based plasmas for the growth of multiwall carbon nanotubes. First, we compare the 3-D spatially resolved intensity of a pure argon plasma discharge to that of a typical carbon-hydrogen-argon plasma used for nanostructure growth. We then present an analysis of the species present in the carbon-based plasma, identified by a wavelength scan of the plasma from 300-900 nm, to begin to develop an understanding of the possible plasma and growth chemistries. Next, we present 3-D spatially resolved optical intensity profiles versus pressure for the C-C moiety, as this carbon unit is thought to be significant for nanotube growth. The spatial emission of carbon was observed by looking at the 516.5 nm band head of the C2 Swan band. Finally, we present an analysis of the hydrogen rotational temperature versus pressure and temperature versus power. Our measurements indicated gas temperature conditions of about 440-540 K (167-267 /spl deg/C).

Carbon nanostructure growth in an inductively coupled plasma

Summary form only given, as follows. Carbon nanostructures have been grown in a modified GEC Reference Cell. The inductively coupled plasma is generated with 500 watts of 13.56 RF power applied to a five turn coil. A second 500 watt RF power supply is used to bias the substrate. The carbon nanostructures were grown on silicon substrates covered with 100E-200 E Fe thin films, which serve as a catalyst. Argon at 100 mT is used as a buffer gas to sustain the inductively coupled mode. Varying ratios of CH/sub 4/ and H/sub 2/ are added to the gas as needed by the growth mechanisms. Several morphologies were obtained. Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution TEM are used to examine the samples. Growth morphologies as a function of plasma and reactor parameters are discussed.

XeCl excimer fluorescence in a microwave discharge

Summary form only given. Ultraviolet light sources are becoming increasingly useful to manufacturing applications such as the curing of inks, coatings, and adhesives. Intensive ultraviolet light can provide efficient curing without intense heat. Microwave driven lamps have many advantages including long lifetime, high overall efficiencies and high intensity emission; XeCl is one of many rare-gas halide excimers used in these systems. The experiment described here is used to understand the production mechanisms of XeCl as well as the optimal conditions for ultraviolet emission. A continuous wave discharge produced by 2.45 GHz microwaves is used to produce 308 nm fluorescence (B/spl rarr/X) and 236 nm fluorescence (D/spl rarr/X). Varying ratios of Xe and Cl/sub 2/, are controlled by mass flow controllers and mixed in a mixing cell before flowing into a quartz tube, which lies along the centerline axis of an Asmussen microwave cavity. The emission of 236 nm tends to be much dimmer than the more prominent 308 nm emission. Emission from Xe atoms are also observed. Pressure ranges from a few torr to over 100 torr are used with microwave powers ranging from 100 W to 300 W. A comparison of the XeCl emission using different ratios of Xe and Cl/sub 2/, and trends in power and pressure will be presented.