József Gyulai

Bio: József Gyulai is an academic researcher from Hungarian Academy of Sciences. The author has contributed to research in topics: Silicon & Ion implantation. The author has an hindex of 29, co-authored 235 publications receiving 4569 citations. Previous affiliations of József Gyulai include Osaka University & University of Erlangen-Nuremberg.

Ion Implantation in Semiconductors

Abstract: Ion implantation is being applied extensively to silicon device technology. Two principle features are utilized- 1) charge control in MOS structures for threshold shift, autoregistration, and complementary wells and 2) distribution control in microwave and bipolar structures. Another feature that has not been extensively exploited is to combine the advantages of the high resolution capabilities of electric beam pattern delineation with the low lateral spread inherent in the implantation process. This talk reviews some of the general features of the characteristics of implanted layers in terms of depth distribution, radiation damage and electron activity. Implantation processes in silicon are reasonably well understood. There remain areas which require further clarification. For compound semiconductors, particularly GaAs, implantation techniques offer attractive possibilities for the fabrication of high frequency devices. In these materials, the substrate temperature during implantation and the dielectric coating required to prevent dissociation during thermal anneal play major roles.

Ion‐induced amorphous and crystalline phase formation in Al/Ni, Al/Pd, and Al/Pt thin films

Abstract: Amorphization by ion beam irradiation of multilayered samples of Al/Pt, Al/Pd, and Al/Ni has been investigated by selected area diffraction and Rutherford backscattering. With a dose of 2×1014 Xe ions/cm2, uniform mixing is achieved in the Al/Pt system and the amorphous phase is produced over a large composition range. In the Al/Pd and Al/Ni systems, amorphous phases or the equilibrium, crystalline phases are formed depending on the composition of the films. The same results were found when the samples were annealed to form crystalline phases before bombardment. For thin films of these fcc metals, only the simplest intermetallics, NiAl and PdAl, (primitive cubic structures with 2 atoms/cell) were formed in crystalline form by ion‐beam irradiation.

Kinetics of TiSi2 formation by thin Ti films on Si

Abstract: Silicide formation with Ti deposited on single crystal Si and Ti deposited on amorphous Si layers sequentially without breaking the vacuum was investigated using backscattering spectrometry and glancing-angle x-ray diffraction. For Ti deposited on amorphous Si, TiSi2 was formed with a rate proportional to (time)^1/2 and an activation energy of 1.8±0.1 eV. For Ti deposited on single crystal Si, the reaction rate was slower and the silicide layer was nonuniform in thickness. We attribute the difference in behavior to the presences of interfacial impurities in the case where Ti was deposited on single crystal Si.

Improvement of Crystalline Quality of Epitaxial Si Layers by Ion-Implantation Techniques

Abstract: We demonstrate that the crystalline quality of Si layers grown on sapphire substrate (SOS) by the CVD method can be greatly improved through the use of implantation of Si ions and subsequent thermal annealing at relatively low temperatures (∼550 °C). This method utilizes an amorphous layer created by ion implantation near the sapphire/Si interface. Subsequent regrowth of this amorphous layer starting from the relatively perfect Si surface region leads to a much improved Si crystalline layer, as evidenced by MeV 4He+ channeling and TEM measurements. When the implantation‐formed amorphous layer is located at the outer portion of the Si layer, thermal annealing leads to only a small reduction in the amount of defects in the regrown layer as compared to the unimplanted sample. In these layers, epitaxial regrowth occurs with the same rate and activation energy observed in self‐ion‐implanted 〈100〉 Si.

Alloying Behavior of Au and Au–Ge on GaAs

Abstract: Although Au–Ge has often been used in making Ohmic contacts to GaAs, the alloying behavior of this system has not been well characterized and understood. In this paper the behavior of Au and Au–Ge layers on GaAs was investigated as a function of processing temperature (400–600°C) and time by backscattering and channeling‐effect measurements with 2‐MeV 4He ions. Scanning electron microscopy and current‐voltage evaluations were also made. Similarities are found in both systems: There is a deeply penetrating component of Au into the GaAs that remains essentially unaltered once the surface Au has been consumed; a disordered region near the surface is found, the amount of which increased with increased process times. No significant amount of Au is found on substitutional or tetrahedral interstitial sites within about 3000 A of the surface. The presence of the Ge does have a significant effect: Complete alloying occurs at lower temperatures, and Ohmic contacts are formed. Scanning‐electron‐microcope displays in...

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Semiconductor device, and manufacturing method thereof

Abstract: 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.

Morphology evolution via self-organization and lateral and vertical diffusion in polymer:fullerene solar cell blends.

Abstract: Morphology evolution via self-organization and lateral and vertical diffusion in polymer:fullerene solar cell blends