Hiroyuki Sanda

Etching Rate Control by MeV O+ Implantation for Laser-Chemical Reaction of Ferrite

The control of etching rate in laser-induced chemical reaction of Mn–Zn ferrite in H3PO4 solution by MeV O+ implantation has been investigated. The etching induced by Ar+-ion laser irradiation in a H3PO4 solution was suppressed by implantating 3 MeV O+ to a dose of 1×1017 cm-2 when the laser power was low. The etching suppression disappeared when the O+-implanted sample was thermally annealed at 850°C for 30 min. The suppression is found to be related to the crystallinity change induced by ion implantation instead of surface reflectivity change.

Fabrication and characterization of CMOSFETs on porous silicon for novel device layer transfer

To develop a new device layer transfer technology with porous layer splitting, CMOS FETs were successfully fabricated on epitaxial layers with different thicknesses over porous silicon for the first time. FETs on more than 300nm thick epitaxial films show satisfactory electrical performance. A fabricated active layer was successfully transferred on a flexible plastic substrate for the first time. Transferred devices also show excellent performance. This technology is applicable to flexible single crystal ICs and to thermal cooling of active layers

Modification of magnetic property in Mn-Zn ferrite by MeV ion implantation

The magnetic property of Mn‐Zn ferrite has been modified by Si+ and Au+ implantation at 3 MeV to doses of 1×1016 and 1×1017 cm−2, respectively. The magnetization of the implanted surface layer decreased to zero when the ion implantation induced vacancy number was high enough. The decrease in magnetization is found to be related to the vacancy number in the implanted layer. The surface magnetization of the implanted layer can be completely recovered by thermal annealing at 850 °C for 30 min.

Two-dimensional porous silicon photonic crystal light emitters

We present design and fabrication of two-dimensional photonic crystal cavities made in nanoporous silicon luminescent at 700-800 nm. Enhancement in photoluminescence extraction efficiency at the resonant wavelength is expected due to Purcell effect.

MeV-ion-beam induced localized enhancement of magnetization in stainless steel foils

MeV ions were implanted into 301 and 304 stainless steel foils to investigate the localized modification of magnetic properties associated with the phase transformation. The intensity of the magnetization was found to increase by MeV Au+ implantation because of the localized martensitic transformation. The increase in magnetization for 301 stainless steel was greater than that for 304 stainless steel because 301 stainless steel more easily transformed austenite into martensite. The beam-induced localized phase transformation in stainless steel can be applied to permanent magnetic recording.

Local Control of Magnetic Property in Stainless Steel Surface by Ion and Laser Beams

MeV ion and Ar-ion laser beams were impinged onto 304 stainless steel foils to investigate the localized modification of the magnetic property associated with the phase transformation. The intensity of the magnetization was found to increase by MeV Au+ implantation because of the localized martensitic transformation, whereas that of the Ar-ion laser-irradiated areas was found to locally decrease at a laser power of 350 mW and almost extinguish at 550 mW with a beam spot size of 13.2 µm (at 1/e intensity) because of the localized retransformation into austenite. These results indicate that the beam-induced localized phase transformation in stainless steel can be applied to permanent magnetic recording.

Photoluminescence decay dynamics of silicon-rich silicon nitride film in photonic crystal nanocavity

We described design and fabrication of the light source, and demonstrated sevenfold photoluminescence (PL) enhancement from a single cavity. In this approach, photonic crystal cavities are used to enhance PL by increasing spontaneous emission rate from Si nanoparticles due to the Purcell effect, and by increasing collection efficiency. Here we report our results on the measured photoluminescence decay time, cavity design optimization, and efficiency of the material.

Silicon-based photonic crystal nanocavity light emitters

We study light emitters based on two-dimensional planar photonic crystal (PC) nanocavities fabricated in silicon rich silicon nitride that exhibits photoluminescence (PL) at 600-800 nm

Control of etching behavior of MnZn ferrite in a laser-chemical reaction by MeV ion beam modification

Laser-induced etching of MnZn ferrite samples implanted with MeV ions has been investigated. The etching induced by Ar+ -laser irradiation in a H3PO4 solution was completely suppressed by implanting 3 MeV Au+ to a dose of 1 × 1016 cm−2 when the laser-induced local temperature rise was below the melting point of the ferrite. The etching suppression disappeared when the Au+ -implanted sample was thermally annealed at 900° C for 30 min. The suppression is found to be related to the crystallinity change induced by ion implantation. The decrease in surface magnetization induced by ion implantation can be recovered by thermal annealing at 900° C for 30 min.

Change in Magnetic Characteristic Of Stainless-Steel by Laser and Ion Beams

Focused Ar-ion laser and MeV ion beams were impinged onto stainless-steel foils to investigate the localized modification of the magnetic property associated with the phase transformation. The magnetic signal intensity of the Ar-ion laser irradiated areas was found to locally decrease at a laser power of 350 mW and almost extinguish at 550 mW with a beam spot size of 13.2 μm (at 1/e intensity) because of the localized retransformation into austenite. On the other hand, the magnetic signal intensity was found to increase by 3 MeV Au + implantation because of the localized martensitic transformation. The magnetic signal for ferromagnetic substrates was much more enhanced than that for non-magnetic substrates. These results indicate that the beam-induced localized phase-transformation in stainless-steel can be applied to fixed magnetic recording.