Plate-like β-FeSi2 bulk crystals with size of 10×10 mm2 and thickness of 1 mm were fabricated by annealing CVT (chemical vapor transport)-grown plate-like α-Fe2Si5 at 800°C in Ar atmosphere. Before annealing, α-Fe2Si5 crystals were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM) to be single crystals with flat surfaces. XRD measurements of β-FeSi2 crystals subjected to annealing showed that they had a po lycrystalline structure. The mean Fe/Si co mposit ion rat io of β-FeSi2 crystal measured by energy dispersive x-ray spectroscopy (EDX) was 31/69 and it was the same as that of α-Fe2Si5 bulk crystal before annealing. SEM, Raman scattering and electron probe micro-analysis (EPMA) measurements identified that there existed small Si precipitates mixed in the matrix of β-FeSi2 crystals. At annealing temperature of 800°C, the plate-like β-FeSi2 bulk was obtained even the annealing duration time was as short as 5 hours.

We investigated the optical, electrical and structural properties of the layer which was implanted with sulfur ion(S+) in 4H-SiC. By using the high temperature ion implantation technique more less residual defects were observed compared with the room temperature ion implantation by Rutherford backscattering spectrometry and channeling(RBS-channeling). After annealing at 1700°C there was no significant difference between the implanted sample and virgin sample in crystallinity within the detection limit of RBS-channeling. From the result of low temperature photoluminescence(LTPL) we could see the photoluminescences, so-called D1 and D2center, originating in the defects formed by ion implantation and post-annealing(∼1700°C) processes and confirmed that their intensities decreased with the increasing of the total dose of S+. The result of Hall effect measurement suggested that the conduction type of S+-implanted layer is n-type and their activation energies were 275meV and 410meV by the fitting of neutrality equation assuming the two activation energies for the hexagonal and cubic lattice sites in 4H-SiC.

Fabrication of Si1-xGex and Si-1-x-yGexCy layers on Si(100) by high-dose ion implantation of 72Ge ions without and with 12C ions and subsequent high-energy and low-energy ion-beam-induced epitaxial crystallization (IBIEC) has been investigated. Structural properties of the surface layers were observed by RBS-channeling technique. Si(100) wafers were implanted with 150keV and 80keV Ge ions at room temperature so as to produce a peak concentration of Ge amounting to approximately 2 and 14 at.%, respectively. C ions were additionally implanted to a fluence of 10% of Ge concentration for the SiGeC samples. IBΓEC experiments performed with 400keV 18Ar ion bombardments have induced crystallization of the amorphous layers of SiGe and SiGeC on Si up to the surface at 400°C for both samples with low Ge concentration (2%) and high Ge concentration (14%). IBIEC using 72Ge ions with energies whose projected ranges are within the amorphous layer was alternatively performed for SiGe layer on Si. Bombardments of 140keV and 40keV Ge ions at 400°C have induced crystallization up to the surface with a slight disorder in the grown layer. Present experimental results suggest a novel ion beam synthesis method of fabrication of SiGe (SiGeC) on Si at low temperatures.

To elucidate the mechanism of dose rate (DR) dependence of electrical activation, following two questions are investigated; why the amount of damage remaining after ion bombardment depends on DR and why it affects the electrical activation after high temperature annealing. From the observation that the DR dependence scales with temperature, the activation energy of recovery during ion irradiation has been estimated to be 0.75 and 1.0 eV. A higher DR suppresses the recovery and results in more damage, which in turn delays the electrical activation of implanted impurities.

Ion beai induced epitaxial crystallization (IBIEC) in preaiorphized BP(100) has been investigated by RBS channeling experiients. Re-crystallization was induced by subsequent ion boibardients with 400 keV Kr, 400 keV Ar and 800 keV Ar at temperature range between 200°C and 450°C. The current densities of Kr and Ar ions were selected to give the saie energy deposition rate in the elastic collision process. Epitaxial crytallization was observed at teiperatures luch below those required for the therial solid phase epitaxy (SPE) process (above 800°C). The critical temperature for crystallization at typical current densities was 230°C. The ion species used for the preaiorphization give a weak influence on the regrowth rate. On the scale of deposited energy density in the elastic collisions, ion boibardients with higher electronic excitation efficiency were found to be effective in the regrowth process. Dose rate is found to be of iiportance in the regrowth process. The activation energy observed in Ar ion boibardients was 0.18±0.05 eV.