Katsuji Haruna

Thermal Expansion Coefficient of Synthetic Diamond Single Crystal at Low Temperatures

The lattice parameter of synthetic diamond single crystals has been measured in the range 4.2-320 K by the X-ray diffraction method. The lattice parameter is found to be nearly constant between 4.2 and 90 K. The thermal expansion coefficient α calculated from the experimental results is very small (of the order of 10-7 or less) and no definite evidence of the negative thermal expansion is found within our relative experimental accuracy of the order of ±1×10-6.

The thermal expansion coefficient and Gruneisen parameter of InP crystal at low temperatures

The thermal expansion of the lattice constant of InP crystal has been measured in the range 4.2-300 K by the Bond method and the results are shown graphically. The thermal expansion coefficient alpha calculated from the experimental results is negative between 15 and 80 K and positive below 15 K. The corresponding Gruneisen parameter gamma closely follows the behaviour of alpha and the values of alpha and gamma are tabulated and shown graphically. The results do not agree with the phenomenological theory in which only a negative alpha is predicted for InP at low temperatures.

Thermal expansion of a boron-doped diamond single crystal at low temperatures

The lattice parameter of a single-crystal boron-doped synthetic diamond has been measured in the range 4.2-300 K by x-ray diffraction (Bond method), with precision . Over the whole range the results are consistent with A, where T is the absolute temperature. The dilation due to doping indicates a boron concentration of about 100 ppm. The increase of thermal expansion over that of an undoped synthetic diamond is found to be unexpectedly large (10-15%), giving an apparent dilation on doping that is markedly temperature dependent.

The negative thermal expansion coefficient of GaP crystal at low temperatures

The thermal expansion of the lattice constant of a GaP crystal was measured in the range 4.2-300K using the Bond method. The authors found a negative thermal expansion coefficient for GaP at low temperatures. They also calculated the Gruneisen parameter and this was negative below 50K. These experimental results do not agree with the phenomenological theory in which a positive thermal expansion coefficient for GaP is predicted at low temperatures.

Carrier Concentration Dependence of Negative Longitudinal Magnetoresistance for n-InSb at 77 K

Reliable dependences of negative longitudinal magnetoresistance (NLM) for n-type InSb on carrier concentration n and on mobility ? are investigated at 77 K up to 1.8 T with a number of specimens, whose n range from 5?1013 cm-3 to 4?1017 cm-3 and ? from 7?105 cm2/V?s to 4?104 cm2/V?s. The maximum NLM, ?// (1.8 T)/?0?0.5, occurs at n?3?1015 cm-3 and correspondingly at ??2?105 cm2/V?s just before the occurrence of carrier degeneracy (n=4?1015 cm-3 at 77 K) in accordance with existing theories. NLM disappears with increasing n because of degeneracy, while it becomes less negative with decreasing n due to decreasing ionized impurity scattering and crystal inhomogeneity. The disappearance of NLM at n<1?1014 cm-3 is revived by the annealing process to remove inhomogeneity.

Effect of ion beam irradiation in amorphous ferromagnetic alloys

Abstract The effect of high energy B-ion beam irradiation on the soft magnetic properties of Fe-based amorphous ferromagnetic alloys, FeCuNbSiB and FeBSiC, has been investigated by measuring hysteresis loops. The improvement of soft magnetic properties is found to be better than in the case of high energy P-ion irradiation. The increase of permeability at the initial stage of B-ion irradiation in FeCuNbSiB amorphous alloy was significant.

X-ray diffraction studies of self-ion irradiated synthetic single crystal diamond

Abstract Synthetic single crystal diamonds were irradiated with 100 MeV carbon ions up to a fluence of 3.6×10 15 ions/cm 2 at about 100 K and with 3 MeV electrons up to 1×10 19 e/cm 2 at 60°C. Volume changes after irradiation were studied by means of lattice parameter measurements by X-ray diffraction, indicating linear increases of the lattice parameter with fluence. A drastic increase of the integrated intensity of the scattered X-ray was observed after ion irradiation, and a large increase after electron irradiation. The drastic change is due to the so-called “disappearance of the extinction effects” in the dynamical diffraction theory, which is associated with the introduction of defects by the irradiation. The integrated scattering intensity in diamond is very sensitive to the amount of defects produced by the irradiation.

Two step rapid heating reflow of borophosphosilicate glass and estimation for a coefficient of heating delay by thermal analyses

The reflow of borophosphosilicate glass (BPSG) was studied by the rapid heating technique in two step irradiations using a halogen lamp. Pre-annealing (800? C, 30 s) during the first step irradiation, which aims to reduce the heating delay for the BPSG film, was carried out prior to high temperature heating (1050?1200? C, 20 s). The reflow angle with pre-annealing is consistently smaller than that without pre-annealing. Moreover, the reflow difference between with pre-annealing and without pre annealing decreases with increasing temperature because the heating delay for the BPSG film increases. The heating delay is primarily caused by thermal resistance between the film and the silicon wafer because, as the result obtained from the finite element method indicated, the heat conduction delay between the film surfaces was negligibly small. The equation for heat resistance can be solved analytically and the thermal resistance coefficient can be estimated by this solution, using the physical parameters of the film and the experimental results.

Horizontal Zone-Melting of Indium Antimonide in Vacuum. II. Characterization by Galvanomagnetic Measurements at 77 K

Magnetoresistance and transverse magnetophonon resonance data at 77 K for n-type InSb crystals (prepared by the method described in Part I) are given, with the aim of detecting residual impurities and inhomogeneities. The importance of 1) using boat material not wetted by InSb and 2) low-temperature annealing (at 200°C for one week) are shown experimentally. The concentration of residual impurities is estimated to be 2×1014/cm3, and three kinds of impurity are found. Furthermore, dislocations and non-uniform distribution of the compensating acceptor impurities are identified as the source of inhomogeneities. It is concluded that the carrier concentration of less than 1014/cm3 is due to the compensation effect and that the reliable maximum mobility at 77 K is 8×105cm2/Vs.

Induced Magnetic Anisotropy in Amorphous Ferromagnetic alloys by Ion Beam Irradiation

Amorphous ferromagnetic alloy, Fe-Cu-Nb-Si-B and Fe-B-Si-C were irradiated with high energy ion beams, and the differences in the magnetic properties before and after the irradiation were investigated by measuring low field magnetic hysteresis loops. It was found that in the early stage of the irradiation the soft magnetic properties improved. After a long irradiation, however, they deteriorated.