Visible photoluminescence around an orange band of 580 nm wavelength are observed from 300 nm thin SiO2 layers implanted by Si or Ge ions at both substrate temperatures of 25 °C [room temperature (RT)] and 400 °C (hot). Si implantations at an energy of 30 keV were performed with doses of 5×1015, 3×1016, and 1×1017 cm−2 while Ge implantations were done at 100 keV with a dose of 5×1015 cm−2. Samples implanted at 400 °C always show much higher intensities of luminescence than those implanted at room temperature. Electron spin resonance signals of the hot-implanted samples indicate relatively smaller amounts of nonradiative defects than those of RT-implanted samples. It is concluded that the hot-implantation effectively enhances the intensity of defect-related photoluminescence by reducing the density of the nonradiative defects and introducing the radiative defects, which contribute to the luminescence in SiO2 layers.

Heteroepitaxial growth behavior of SrRuO 3 / SrTiO 3 (001) by pulsed laser depositionHeteroepitaxial Y 2 O 3 films were grown on an Si͑111͒ substrate by ion assisted evaporation in an ultrahigh vacuum, and their properties such as crystallinity, film stress, and morphological change were investigated using the various measurement methods. The crystallinity was assessed by x-ray diffraction ͑XRD͒ and reflection high-energy electron diffraction. Interface crystallinity was also examined by Rutherford backscattering spectroscopy ͑RBS͒ channeling and transmission electron microscopy. The strain of the films was measured by RBS channeling and XRD. Surface and interface morphological characteristics were observed by atomic force microscopy and x-ray scattering method. By comparing the interface with the surface characteristics, we can conclude that many defects at the interface region were generated by interface interaction between the yttrium metal and Si substrate. Moreover, the film quality dominantly depended on the deposition temperature. The crystallinity was greatly improved and the surface roughness was drastically decreased in the temperature range 500-600°C. On the other hand, in the temperature range 600-700°C, the compressive stress and film density were further increased, and the island size decreased. Also, the shape of the surface islands was transformed from elliptical to triangular. The film stress was found primarily at the interface area because of the interaction between yttrium and Si substrate.

Titanium oxide films were deposited on bare glass and boiled glass in 50% H2SO4 for 30 min at various substrate temperatures by metal-organic chemical vapor deposition. We investigated the effects of a substrate temperature between 300 and 550 °C on such properties as thermal stability, deposition rate, and chemical states of the films. The thickness of the films is independent of the substrate treatments. The deposition rate of the films is linearly decreased with increasing substrate temperature. Rutherford backscattering spectroscopy and x-ray photoelectron spectroscopy results indicate that the H2SO4 treated glass substrate is superior to the bare glass substrate in the suppression of out-diffusion of sodium and calcium through the TiO2 film till a substrate temperature of 500 °C. There exist only Ti3+ and Ti4+ oxidation states in the film regardless of a substrate temperature and substrate treatment. Ti3+ fractional composition are changed slightly between 0.11 and 0.17 and Ti4+ fractional composition are changed between 0.82 and 0.90 with varying substrate temperature.

The increase of bit density is a critical point in the magnetic storage media. We intend to manipulate the easy axis in ferromagnetic thin films with ion irradiation technique. Co/Pt multilayered films were prepared for the study and then were ion-irradiated while an external magnetic field was applied to them. In consequence, we get a CoPt alloy film with an in-plane easy axis and change its direction with an external magnetic field applied during the irradiation. The energetic ion beam let the ferromagnetic film have a new atomic and magnetic structure. 1 Introduction Magnetic recording system is one of the most rapidly developing field of high technology in the world today. One of the most critical point for it is raising the recording density at which information can be stored in a media. This is concerned with the signal to noise ratio and the stability of smaller bits. In recent years, the areal density of the magnetic storage media, especially of the platter in hard disk drives, has been increased at a rate of up to 60% per annum [1 -4]. As the bit density of them gets much higher, that is, the bit size does even smaller, magnetic easy axis manipulation has attracted a lot of attention in the technology [5,6]. In common uniaxial recording, magnetic dipole interactions between neighboring bit areas may lead to a reversal of data bits and cross track interference that limit the ability to accomplish ultrahigh storage density [1,7]. Since the interaction energy between adjacent domains is proportional to the cosine of the angle between magnetization directions, it can be reduced by making the direction of adjacent anisotropies relatively orthogonal.In this paper, we attempt to make an in-plane easy axis in a ferromagnetic thin film that will be indispensable for the media with ultrahigh recording density, and then change its direction to the designed one. We choose a Co/Pt multilayered film for the sample, since it has good magnetic properties and its alloy is a main constituent of the platter in hard disk drives [8 -11]. Ion irradiation, our method, has the advantage in forming a metastable alloy, which has different characteristics from that of thermodynamically stable one, by putting inert ions in the multilayered film. We can call it the ion-beam-mixing process. When energetic ions with energy of several tens of keV penetrate a thin film, the collision cascades cause displacements of the target atoms, produce a new mixed phase through the intermixing of cobalt and platinum sublayers [12,13], and then get a metastable physe as a result of rapid quenching [14,15].

Manipulation of magnetic anisotropy in ferromagnetic thin films was tried with ion-beam-mixing technique. Co/Pt multilayered films were deposited on Si(100) by electron beam evaporation and mixed with an energetic Ar + ion-beam under external magnetic field which was parallel to the sample surface. The magnetic easy axis was observed from the ion-beam-mixed samples along the direction of applied external magnetic field. When the ion dose was less than a critical dose, a small peak was measured along the magnetic hard axis. The small peak disappeared after ion-beam-mixing with a dose higher than the critical one.