M. Yamada 교수

Abstract Electrical injection of spin-polarized electrons from ferromagnets into semiconductors has been generally demonstrated through a tunneling process with insulator barrier layers that can dominate the device performance, including the electric power at the electrodes. Here, we show an efficient spin injection technique for a semiconductor using an atomically controlled ferromagnet/ferromagnet/semiconductor heterostructure with low-resistive Schottky-tunnel barriers. On the basis of symmet

We demonstrate the formation of abrupt phosphorus (P) δ-doping profiles in germanium (Ge) by the insertion of ultra-thin silicon (Si) layers. The Si layers at the δ-doping region significantly suppress the surface segregation of P during the molecular beam epitaxial growth of Ge and high-concentration active P donors are confined within a few nm of the initial doping position. The current-voltage characteristics of the P δ-doped layers with Si insertion show excellent Ohmic behaviors with low en

We experimentally show that the spin relaxation in degenerate $n$-type germanium (${n}^{+}$-Ge) depends strongly on the concentration of the donor impurity (${N}_{\mathrm{d}}$) at low temperatures. From measuring nonlocal spin signals for various lateral spin-valve devices at 8 and 77 K, the spin diffusion length (${\ensuremath{\lambda}}_{\mathrm{Ge}}$) of ${n}^{+}$-Ge can be estimated as a function of carrier concentration ($n$), i.e., ${N}_{\mathrm{d}}\ensuremath{\approx}n$ ($\ensuremath{\sim}

A multilevel storage (MLS) structure for high density CCD memory is proposed and demonstrated. Using four levels of charge, 2 bits can be stored in one storage cell. Stored charge is transferred by a clocking scheme which provides larger charge-carrying capacity without increasing memory cell size. These techniques make it possible to achieve high packing density without requiring fine patterning.

A novel Hi-C RAM cell is proposed for reducing the alpha-particle-induced soft error rate. The novel cell utilizes the doubly-implanted Hi-C struture combined with the boosted storage gate, which provides much alignment tolerance to the implantation steps for the Hi-C cell. This Hi-C cell having a charge storage capacity 30% larger than that of the conventional cell results in one order of magnitude decrease in soft errors as compared with the conventional one. The concept of this excellent cell

Utilizing a Si0.1Ge0.9 layer grown on Ge/Si(111) as a spin-transport channel and a Co2FeAl0.5Si0.5 ferromagnetic epilayer as a spin injector and detector, we demonstrate two-terminal local magnetoresistance signals at low temperatures in SiGe based lateral spin-valve devices. The magnitude of the local magnetoresistance signals is twice as large as that of nonlocal signals below 50 K. The local magnetoresistance signal can be observed up to 225 K, at which the nonlocal magnetoresistance signals

We report the highest two-terminal magnetoresistance (MR) ratio at room temperature in semiconductor (SC)-based vertical spin-valve (VSV) devices on a silicon (Si) platform. Here, we demonstrate all-epitaxial ferromagnet (FM)–germanium (Ge)–FM VSV devices with Co2FeSi as one of two FM electrodes. In addition to the high spin polarization of Co2FeSi, the relatively low resistance in the parallel magnetization state due to the strong Fermi-level-pinning effect at the p-type Ge/Co2FeSi interface ca

14β-Acetoxycodeinon und 14β-Bromcodeinon wurden mit T. sanguinea umgesetzt, wobei sich 14β-Hydroxycodein als gemeinsames Produkt gewinnen lieβ.

Using artificially controlled ferromagnet (FM)–semiconductor (SC) interfaces, we study the decay of the nonlocal spin signals with increasing temperature in SC-based lateral spin-valve devices. When more than five atomic layers of Fe are inserted at the FM/SC interfaces, the temperature-dependent spin injection/detection efficiency (Pinj/det) can be interpreted in terms of the T32 law, meaning a model of the thermally excited spin waves in the FM electrodes. For the FM/SC interfaces with the ins

Using pure spin current transport measurements in lateral spin-valve devices, we study the spin relaxation in an $n$-type nondegenerate Ge layer, which is moderately doped Ge (P: $\ensuremath{\sim}{10}^{18}$ ${\mathrm{cm}}^{\ensuremath{-}3}$). The obtained spin diffusion length $({\ensuremath{\lambda}}_{\mathrm{Ge}})$ of the nondegenerate Ge is two to three times greater than that of heavily doped degenerate Ge (P: $\ensuremath{\sim}{10}^{19}$ ${\mathrm{cm}}^{\ensuremath{-}3}$) in the temperatur