Incubation Time Measurements in Thin-Film Deposition

Studies on the initial growth or nucleation of materials and research on selective deposition often mention an incubation time. Many techniques exist to determine the incubation time. The outcome can be very different for each technique when the same nucleation process is considered. For the first time we have given a simple model which shows that several incubation times can be expected if different methods are used. One of the most popular methods, plotting the mass or thickness as a function of time and defining the incubation time as the intercept on the x-axis, is not a good method. In particular, a meaningful incubation time is found only if a layer-by-layer growth mechanism occurs right from the start. Ellipsometry can be used in situ and is a much more sensitive method, but this technique needs more research to correlate the nucleation process with the data obtained using this technique. The determination of the nucleus density using scanning electron microscopy or atomic force microscope is the most accurate method, yet needs a lot of experiments. Without a detailed description of the measurement method the incubation time is a meaningless quantity

Furnace and rapid thermal crystallization of amorphous GexSi1-x and Si for thin film transistors

The crystallization behavior of polycrystalline silicon (Si) and germanium-silicon alloys (GexSi1−x) from SiH4 and GeH4, where x is in the range of 0-0.32, has been investigated for thin film transistor (TFT) applications. Furnace anneals as well as rapid thermal anneal (RTA) and combinations of these two techniques have been used to crystallize amorphously deposited thin (≤100 nm) films. The effects of time and temperature for the furnace anneals and time, temperature and pulse rate for the RTA have been investigated. Smooth Si and GexSi1−x layers with a surface roughness ≤0.6 nm have been obtained using an initial Si layer for the GexSi1−x material, since GexSi1−x shows a nucleation problem on oxide surfaces which influences the resulting surface roughness and grain size. For TFT applications the optimal film properties cannot be obtained with a single crystallization anneal. Conventional furnace crystallization results in smooth layers with Si furnace crystallized films exhibiting small grains with many intra-grain defects. An average grain size of approximately 300 nm for Ge0.25Si0.75 and slightly larger grains for Ge0.32Si0.68 with less defects is obtained at lower temperature. RTA results for Si and GexSi1−x in fine grained material with lower defect density

The origin of carbon isotope vital effects in coccolith calcite

Calcite microfossils are widely used to study climate and oceanography in Earth’s geological past. Coccoliths, readily preserved calcite plates produced by a group of single-celled surface-ocean dwelling algae called coccolithophores, have formed a significant fraction of marine sediments since the Late Triassic. However, unlike the shells of foraminifera, their zooplankton counterparts, coccoliths remain underused in palaeo-reconstructions. Precipitated in an intracellular chemical and isotopic microenvironment, coccolith calcite exhibits large and enigmatic departures from the isotopic composition of abiogenic calcite, known as vital effects. Here we show that the calcification to carbon fixation ratio determines whether coccolith calcite is isotopically heavier or lighter than abiogenic calcite, and that the size of the deviation is determined by the degree of carbon utilization. We discuss the theoretical potential for, and current limitations of, coccolith-based CO2 paleobarometry, that may eventually facilitate use of the ubiquitous and geologically extensive sedimentary archive

Device for producing and enclosing a hot plasma

1391103 High-frequency discharge tubes EUROPEAN ATOMIC ENERGY COM- MUNITY 24 July 1972 [23 July 1971] 34566/72 Heading H1D A device for producing and enclosing a hot plasma comprises a toroidal vessel 1 having means 2 for generating a magnetic field along the azimuthal axis 3 of the torus to induce annular electric currents along said axis, and means 6, 7 for generating an oscillating electric field in the vessel having a component parallel to the magnetic field and a frequency at or near the bounce frequency (i.e. about ten times the collison frequency of ions.) A second toroidal vessel or liner 4 is disposed in the first vessel 1, and the diameter of the plasma is limited by annular discs 5. The electric field is generated by annular electrodes 6 and 7 disposed above and below the axis 3 and connected through insulated ducts 8 to a generator producing oscillations having a fre- quency between 10 and 100 KHz. The electric field may alternatively be produced by an aerial disposed in an aperture in the vessel wall and fed with a signal having a fundamental frequency corresponding to the plasma frequency which is amplitude modulated at the bounce frequency

Submicron Systems Architecture: Semiannual Technical Report

No abstract available

Plasmas and Controlled Nuclear Fusion

Contains reports on two research projects.U. S. Atomic Energy Commission (Contract AT(11-1)-3070

Photonic crystal fibers as miniature monitoring platforms for petroleum characterization

A fiber design that allows the characterization of high and low refractive index materials is proposed and demonstrated. This fiber consists of an air-silica photonic crystal fiber supporting a Gaussian like mode confined in the fiber core and a ring mode in a region between the structured area and the fiber cladding. This versatile fiber design finds applications in the oil industry where materials of different refractive indices are found. The characterization of petroleum and CO2 using the new fiber is demonstrated. © 2012 SPIE

Submicron Systems Architecture: Semiannual Technical Report

No abstract available