Kazuo Kajiwara

Shrinkage and growth of oxidation stacking faults during thermal nitridation of silicon and oxidized silicon

We have studied the shrinkage and growth of preexisting oxidation‐induced stacking faults during thermal nitridation of silicon without oxide film and of oxidized silicon with oxide film 23 to 5600 A thick. Nitridation was carried out at 1050 to 1200 °C under ammonia partial pressures of 10−3 to 4 kg/cm2. We observed that stacking faults in silicon without oxide film shrink linearly with nitridation time and their shrinkage rate increased as the partial pressure of ammonia increased. On the other hand, stacking faults in oxidized silicon with oxide film grew during nitridation and their growth rate increased with the increase of ammonia partial pressure after the pressure reached about 10−1 kg/cm2 and with the increase of the thickness of the oxide film. Based on these results, we have proposed a model which assumes that in the shrinkage phenomenon, an undersaturation of silicon self‐interstitials occurs near the silicon surface because of silicon‐cation migration from the silicon‐nitride interface to the...

Structure of MOCVD Grown AlAs/GaAs Hetero-Interfaces Observed by Transmission Electron Microscopy

AlAs/GaAs monolayer scale superlattices were grown by atmospheric pressure-MOCVD and the layer structure was observed with a transmission electron microscope (TEM). Clear stripes with high contrast in the TEM lattice image indicated ultra-abrupt hetero-interfaces. The TEM image and the transmission electron diffraction pattern of the superlattices showed that the hetero-interface was nearly free of island-like structure even in such a very short period superlattice as (AlAs)5-(GaAs)2.

GaAs whiskers grown by a thermal decomposition method

Abstract Gallium arsenide whiskers have been grown on GaAs substrate by a thermal decomposition method using AsH3 and trimethyl gallium (or triethyl gallium). The whiskers were single crystal hexagonal needles with [111] growth direction and (110) lateral faces. A new morphology was observed near the tip of the whiskers. The whiskers had feeler-like micro whiskers at the tip and had many humps on the side faces near the tip. The results of electron probe micro analysis suggested that there existed a gallium droplet at the tip of the whiskers during the growth. The growth mechanism of the whiskers was concluded to be basically the vapor-liquid-solid mechanism.

Excimer‐laser annealed ohmic contacts to n‐GaAs substrates through an ultrathin reacted layer

An excimer laser has been employed to form ohmic contacts to n‐GaAs substrates through an ultrathin reacted layer. An eutectic AuGe alloy, Ni/AuGe (/n‐GaAs), and AuGe/Ni (/n‐GaAs) were used as ohmic metals. The lowest specific contact resistance ρc measured using the transmission line method was 6.2×10−7 Ω cm2, 2×10−6 Ω cm2, and 1.5×10−6 Ω cm2 for AuGe, Ni/AuGe and AuGe/Ni, respectively. Good surface morphology was also obtained. Depth profiles of the contacts analyzed by an Auger electron microscope show that the thickness of the transition region between the ohmic metal and GaAs was about 100 A for AuGe and Ni/AuGe, and 300–400 A for AuGe/Ni.

Auger spectroscopy analysis of metal/ferrite interface layer in metal-in-gap magnetic head

It is well known that a poor magnetic layer is formed at the interface between the metal film (e.g. Sendust) and the ferrite core in fabricating metal-in-gap heads. The authors have analyzed precisely the poor magnetic layer by means of Auger spectroscopy combined with ion sputtering. It is found that the poor magnetic layer is formed by reaction at the interface between the metal film and the substrate during the annealing process. In the case of Sendust, this layer is composed of Al/sub 2/O/sub 3/+SiO/sub 2/, which is a nonmagnetic material. For a new soft magnetic alloy, Fe-Ga-Si-Ru, used instead of sendust, the reacted layer is composed of SiO/sub 2//Ga/sub 2/O/sub 3/. To prevent the reaction, a very thin intermediate film of SiO/sub 2/ or Si-N-O was formed by sputtering. >

Analysis of metal-ferrite interface layers in metal-in-gap heads

A metal-in-gap head structure in which the metal/ferrite interface is perfectly parallel to the main gap face was adopted for mass-production. An analysis of a pseudo-gap formed at the metal-ferrite interface by using sputter-assisted Auger electron spectroscopy is reported. In the case of a Sendust MIG head, it is confirmed that the pseudo-gap is a reacted layer at the metal-ferrite interface, which consists of Al/sub 2/O/sub 3/+SiO/sub 2/. The reaction mechanism is examined in the case of Sendust/MnZn-ferrite and a soft magnetic alloy, called Sofmax, and suitable barrier materials and thickness ranges. It is found that the reacted layer is reduced drastically by using a SiO/sub 2/ or SiN/sub 2/O 5-10 nm thick ultrathin barrier layer and Sofmax alloy film instead of Sendust. The ripple of a parallel-type metal-in-gap heads is found to be 0.5 dB or less. >

Monte Carlo Simulation for Auger Depth Profiling of GaAs/AlAs Superlattice Structure by Ar^+ Ion Sputtering

A dynamical Monte Carlo simulation including surface recession has been performed to understand the internal atomic mixing process in Auger depth profiling of a GaAs/AlAs superlattice with Ar+ ion sputtering. Results obtained for 1.0 keV Ar+ at an incidence angle of 80° show that the sputtering rates in AlAs layer and GaAs layer are almost the same and the depth resolutions at the GaAs/AlAs interface in the Al depth profile are 2.9 nm and 3.8 nm for low-energy (68 eV) and high-energy (1396 eV) Al Auger peaks, respectively. Although these values are slightly larger than those obtained from experiments, the present model describes the atomic mixing process during sputter depth profiling with considerable success.

41.3: Luminescence Deterioration of Blue-Emitting ZnS: Ag, Cl Phosphors in High-Voltage FEDs

Aluminized screens by using two conventional blue-emitting P22B phosphors were prepared for high-voltage FEDs. Aged phosphors in FEDs were studied by cross-sectional transmission electron microscopy. Deterioration mechanism of luminescence of P22B phosphors is described in this work.

4.1: Blue‐emitting ZnS: Ag, Al Phosphor with Longer Lifetime and Saturationless Performance for Projection CRTs

A blue-emitting ZnS: Ag, Al phosphor with low defect density has been developed successfully for projection CRTs. Good crystallinity was verified by cross-sectional transmission electron microscopy. As a result, higher luminescence efficiency, good linearity, and longer luminescence lifetime are obtained in 7-inch projection CRTs.

Toroidal defect at the heterointerface between GaAs and AlxGa1−xAs epitaxial layer

Abstract A morphological defect with the shape of a torus was observed at the heterointerfaces between GaAs and Al x Ga 1- x As layer grown by liquid phase epitaxy. The structure of the toroidal defect was investigated, and it was found that the defect was composed of a region with aluminum content different from that of the surrounding normal region. The toroidal defect is believed to be caused by inhomogeneous mixing of solutions during sliding due to oxygen contamination.