We report calculations of electron inelastic mean free paths (IMFPs) of 50–2000 eV electrons for a group of 14 organic compounds: 26-n-paraffin, adenine, β-carotene, bovine plasma albumin, deoxyribonucleic acid, diphenylhexatriene, guanine, kapton, polyacetylene, poly(butene-1-sulfone), polyethylene, polymethylmethacrylate, polystyrene and poly(2-vinylpyridine). The computed IMFPs for these compounds showed greater similarities in magnitude and in the dependences on electron energy than was found in our previous calculations for groups of elements and inorganic compounds (Papers II and III in this series). Comparison of the IMFPs for the organic compounds with values obtained from our predictive IMFP formula TPP-2 showed systematic differences of ∼40%. These differences are due to the extrapolation of TPP-2 from the regime of mainly high-density elements (from which it had been developed and tested) to the low-density materials such as the organic compounds. We analyzed the IMFP data for the groups of elements and organic compounds together and derived a modified empirical expression for one of the parameters in our predictive IMFP equation. The modified equation, denoted TPP-2M, is believed to be satisfactory for estimating IMFPs in elements, inorganic compounds and organic compounds.

Calculations of electron inelastic mean free paths. III. Data for 15 inorganic compounds over the 50–2000 eV range

An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Semiconductor device, and manufacturing method thereof

In electronic displays or imaging units, the control of pixels is achieved by an array of transistors. These transistors are in a thin film form and arranged in a two-dimensional configuration to form switching circuits, driving circuits or even read-out circuits. In this invention, thin film transistors and circuits with indium oxide-based channel layers are provided. These thin film transistors and circuits may be fabricated at low temperatures on various substrates and with high charge carrier mobilities. In addition to conventional rigid substrates, the present thin film transistors and circuits are particularly suited for the fabrication on flexible and transparent substrates for electronic display and imaging applications. Methods for the fabrication of the thin film transistors with indium oxide-based channels are provided.

Indium oxide-based thin film transistors and circuits

We present new calculations of electron inelastic mean free paths (IMFPs) for 200–2000 eV electrons in 27 elements (C, Mg, Al, Si, Ti, V, Cr, Fe, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Hf, Ta, W, Re, Os, Ir, Pt, Au and Bi) and four compounds (LiF, SiO2, ZnS and Al2O3). These calculations are based on an algorithm due to Penn which makes use of experimental optical data (to represent the dependence of the inelastic scattering probability on energy loss) and the theoretical Lindhard dielectric function (to represent the dependence of the scattering probability on momentum transfer). Our calculated IMFPs were fitted to the Bethe equation for inelastic electron scattering in matter; the two parameters in the Bethe equation were then empirically related to several material constants. The resulting general IMFP formula is believed to be useful for predicting the IMFP dependence on electron energy for a given material and the material-dependence for a given energy. The new formula also appears to be a reasonable but more approximate guide to electron attenuation lengths.

Calculations of electron inelastic mean free paths for 31 materials

The outstanding properties of SiO2, which include high resistivity, excellent dielectric strength, a large band gap, a high melting point, and a native, low defect density interface with Si, are in large part responsible for enabling the microelectronics revolution. The Si/SiO2 interface, which forms the heart of the modern metal–oxide–semiconductor field effect transistor, the building block of the integrated circuit, is arguably the worlds most economically and technologically important materials interface. This article summarizes recent progress and current scientific understanding of ultrathin (<4 nm) SiO2 and Si–O–N (silicon oxynitride) gate dielectrics on Si based devices. We will emphasize an understanding of the limits of these gate dielectrics, i.e., how their continuously shrinking thickness, dictated by integrated circuit device scaling, results in physical and electrical property changes that impose limits on their usefulness. We observe, in conclusion, that although Si microelectronic devices...

Ultrathin (<4 nm) SiO2 and Si-O-N gate dielectric layers for silicon microelectronics: Understanding the processing, structure, and physical and electrical limits

A low temperature thermal cleaning method for Si molecular beam epitaxy (MBE) is proposed. This method consists of wet chemical treatment to eliminate carbon contaminants on Si substrates, thin oxide film formation to protect the clean Si surface from contamination during processing before MBE growth, and desorption of the thin oxide film under UHV. The passivative oxide can be removed at temperatures below 800°C. It is confirmed that Si epitaxial growth can take place on substrates cleaned by this method and that high quality Si layers with dislocations of fewer than 100/cm2 and high mobility comparable to good bulk materials are formed. Surface cleanliness, the nature of thin passivative oxide films, and cleaning processes are also studied by using such surface analytic methods as Auger electron spectroscopy, reflection high energy electron diffraction, and x‐ray photoelectron spectroscopy.

https://iopscience.iop.org/article/10.1149/1.2108651/pdf

Low Temperature Surface Cleaning of Silicon and Its Application to Silicon MBE

ESCA (electron spectroscopy for chemical analysis) measurement results on thin SiO2/Si samples are examined comprehensively, critically, and in detail to show that it is possible to correlate these results with MOS (metal–oxide–semiconductor) device characteristics such as flatband (threshold) voltage, oxide breakdown field, mobile‐ion density, hole and electron trap density, and hot‐carrier lifetime. Up to now, much effort has been made to detect SiOx phases at SiO2/Si interfaces since they are thought to have a significant effect on MOS device characteristics. However, correlating the SiOx phases with device characteristics is difficult and involves overcoming two problems. First, the chemical state is difficult to determine exactly due to x‐ray irradiation effects. Second, the amount of defects and impurities which influence device characteristics is usually below the ESCA detection limit (1012–1013 cm−2) in device‐quality SiO2/Si samples. Investigation of the first problem led to the conclusion that i...

Electron spectroscopic analysis of the SiO2/Si system and correlation with metal–oxide–semiconductor device characteristics

SiSiO2 interface characterization by ESCA

The present invention discloses a semiconductor device comprising a semiconductor layer being made of monocrystalline silicon or silicon-germanium alloy and a semiconductor layer being made of silicon-germanium-carbon alloy formed thereon, wherein the two layers form a heterojunction therebetween. In such a device, no lattice mismatch occurs between the layers or even if lattice mismatch occurs, it is only slight, so that the silicon-germanium-carbon alloy layer is in no danger of causing misfit dislocation therein.

Semiconductor device with crystalline silicon-germanium-carbon alloy

We screened bright blue phosphor materials for a ZnO–WO3 binary system. The film was deposited by combinatorial pulsed laser deposition at room temperature and then annealed. The film composition changes continuously in a full-range from ZnO to WO3 on a single substrate. We obtained two results from the distribution of blue emission-intensity observed by cathodoluminescence of the film: (1) not only did the film have a W composition of 50 mol % (stoichiometric ZnWO4 as the well-known blue phosphor material) but also the W composition region from 45 to 60 mol % had the most emissive phase, and (2) two emissive phases other than the ZnWO4, which have not been described in the phase diagram, were found in the W composition region from 10 to 20 mol % and from 65 to 75 mol %.

Akitoshi Ishizaka

Papers

Low Temperature Surface Cleaning of Silicon and Its Application to Silicon MBE

Electron spectroscopic analysis of the SiO2/Si system and correlation with metal–oxide–semiconductor device characteristics

SiSiO2 interface characterization by ESCA

Semiconductor device with crystalline silicon-germanium-carbon alloy

Bright blue phosphors in ZnO–WO3 binary system discovered through combinatorial methodology