| 1. |
- Frantti, J, et al.
(författare)
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Neutron diffraction studies of Pb(ZrxTi1-x)O-3 ceramics
- 2000
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Ingår i: JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS. - : INST PURE APPLIED PHYSICS. - 0021-4922. ; 39:9B, s. 5697-5703
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Tidskriftsartikel (refereegranskat)abstract
- Neutron diffraction studies of lead zirconate titanate Pb(ZrxT1-x)O-3 (PZT) powders, 0.20 less than or equal to x less than or equal to 0.54, were carried out at 10 K and 297 K, The phase transition predicted by our earlier Raman observations (J. Frantti,
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| 2. |
- Gogova, Daniela, et al.
(författare)
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Optical and structural characteristics of virtually unstrained bulk-like GaN
- 2004
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Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 43:4A, s. 1264-1268
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Tidskriftsartikel (refereegranskat)abstract
- Bulk-like GaN with high structural and optical quality has been attained by hydride vapor-phase exitapy (HVPE). The as-grown 330 mum-thick GaN layer was separated from the sapphire substrate by a laser-induced lift-off process. The full width at half maximum values of the X-ray diffraction (XRD) omega-scans of the free-standing material are 96 and 129 arcsec for the (1 0 -1 4) and (0 0 0 2) reflection, respectively, which rank among the smallest values published so far for free-standing HVPE-GaN. The dislocation density determined by plan-view TEM images is 1-2 x 10(7) cm(-2). Positron annihilation spectroscopy studies show that the concentration of Ga vacancy related defects is about 1.5 x 10(16) cm(-3). The high-resolution XRD, photoluminescence, mu-Raman, and infrared spectroscopic ellipsometry measurements consistently prove that the free-standing material is of high crystalline quality and virtually strain-free. Therefore it is suitable to serve as a substrate for stress-free growth of high-quality III-nitrides based device heterostructures.
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| 3. |
- Hirohashi, Junji, et al.
(författare)
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Embryonic nucleation method for fabrication of uniform periodically poled structures in potassium niobate for wavelength conversion devices
- 2004
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Ingår i: Japanese journal of applied physics. - 0021-4922. ; 43:2, s. 559-566
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Tidskriftsartikel (refereegranskat)abstract
- A new electric poling concept called the 'embryonic nucleation method' for the fabrication of periodically poled structures has been proposed. By applying this method to KNbO3, 1-mm-thick uniform periodically poled KNbO3 (PPKN) with domain inverted period of 35.5 mum and an interaction length of 10 mm has been successfully fabricated by applying only 300 V/mm without the generation of unwanted domains. Furthermore, the reproducibility of the periodic poling process has been greatly improved. SHG using PPKN fabricated by this method was demonstrated and 100 mW second-harmonic laser generation at a wavelength of 532 nm was obtained from 1 W pumping without photorefractive damage at approximately 40 degrees C.
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| 4. |
- Hirohashi, Junji, et al.
(författare)
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Total refraction of p-polarized light at the 90-degree domain boundary in the ferroelectric crystal
- 2004
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Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 43:6A, s. 3413-3418
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Tidskriftsartikel (refereegranskat)abstract
- A 90.DEG.-domain structure was fabricated using electrical poling in ferroelectric birefringent KNbO3 crystal. The refraction and reflection characteristics of the light at the boundary of the 90.DEG.-domain structure were investigated, and the novel behavior of total refraction (no reflection) has been found for the P-polarized light throughout the entire range of incident angle (0.LEQ..THETA..LEQ.90.DEG.). Strong refraction of the light was observed after it exited from the crystal output surface at the incidence parallel to the domain boundary. These behaviors were explained analytically. (author abst.)
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| 5. |
- Imura, M, et al.
(författare)
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3-D flow visualization for construction of the model of the blood flow in the heart
- 2000
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Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 39:5 B, s. 3246-3251
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Tidskriftsartikel (refereegranskat)abstract
- The authors have been developing a model of blood flow in the heart. The flow model of the heart enables us to estimate the entire blood flow of the heart from a couple of 2-D color Doppler images. Therefore, the load on patients is expected to be reduced. To develop the model of the heart, precise observation and an understanding of the blood flow are indispensable, because the flow is strongly related to the diagnosis of heart diseases. The visualization method must have the following features: (1) 3-D (2) objectivity (3) interactivity and (4) multi-aspect. The authors have developed visualization methods to meet the above-mentioned requirements and evaluated the proposed methods with the in-vitro flow data set. The results clearly reveal that the proposed system enables the researchers of the modeling group to obtain the state of entire flow, such as the occurrence of turbulence.
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| 6. |
- Ishio, H
(författare)
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Composition of quantum ratchets with chaotic dots
- 2001
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Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 40:6A, s. 4269-4271
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Tidskriftsartikel (refereegranskat)abstract
- We present a proposal for a new type of quantum ratchets in application of weak-localization (WL) effect in mesoscopic chaotic dots. Coherent electrons transport through the dots under an applied ac voltage and a synchronized pulsating magnetic field. In the first half cycle of the voltage alternation with no magnetic field, the WL effect reduces the electron transmission on average, while the applied magnetic field breaks the time-reversal symmetry in the latter half cycle, suppressing the WL effect. As a result, nonvanishing amount of net electric current in one direction can be measured. We exactly calculate the net electric current which is found accessible in experiments. It is also suggested that the observation of this rectified current is a good quantitative measure of the WL effect in mesoscopic chaotic dots, in contrast with the WL lineshape measurement.
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| 7. |
- Keiper, D., et al.
(författare)
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Metalorganic vapour phase epitaxy growth of InP-based heterojunction bipolar transistors with carbon doped InGaAs base using tertiarybutylarsine and tertiarybutylphosphine in N-2 ambient
- 2000
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Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 39:11, s. 6162-6165
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Tidskriftsartikel (refereegranskat)abstract
- A process for growth of heterostructure bipolar transistors (HBT) using tertiarybutylarsine (TBA) and tertiarybutylphosphine (TBP) in N-2 ambient is realised, which is compatible with a high temperature overgrowth, thus suitable for the vertical integration Of a laser structure on top of an HBT. A high growth temperature for the C-InGaAs base is favourable, to ensure no: degradation during subsequent growth. Increasing the growth temperature after the base from 500 degreesC to 680 degreesC within the emitter layer instead of at the base-emitter interface was found to improve the ideality factors, the de gain and the turn-on voltage.
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| 8. |
- Koh, J. H., et al.
(författare)
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Dielectric relaxation behavior of Ag(Ta,Nb)O-3 interdigital capacitors on oxide substrates
- 2004
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Ingår i: Japanese Journal of Applied Physics. - : IOP Publishing. - 0021-4922 .- 1347-4065. ; 43:4A, s. 1434-1437
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Tidskriftsartikel (refereegranskat)abstract
- The time-dependent dielectric relaxation behavior of Ag(Ta,Nb)O-3 interdigital capacitors was investigated for tunable device applications. Ag(Ta,Nb)03 thin films, which have high k-factor (tunability/ loss tangent), were deposited on the oxide substrates by pulsed laser deposition technique. Ag(Ta,Nb)03 thin film on the LaAlO3 substrate has an epitaxial relationship with the substrate. The observed tunabilities and K-factors of Ag(Ta,Nb)O-3/LaAlO3 and Ag(Ta,Nb)O-3/AI(2)O(3) interdigital capacitors were 5.9% and 17.8 and 3.8% and 9.9, respectively, at 40 V (maximum electric field of 100 kV/cm), 300 K, and 1 MHz. Capacitance relaxation follows the power law C(t) = C-infinity + C-0(t/ls)-(beta) with a very small exponent negligibly fitted in the time domain. Due to this small exponent, the capacitance was changed by less than 0.05% in 2V in 71 s. Time-dependent leakage current was measured by employing the Ag(Ta,Nb)O-3(0.4mum)/Al2O3 interdigital capacitor. The time-dependent relaxation current follows the power law j(t) = j(leak) +j(0)(t/ls)-(alpha) with an exponent alpha = 0-98, j(leak) = 1.14 x 10(-14), and j(0) = 11.42s.
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| 9. |
- Luo, GL, et al.
(författare)
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Growth of high-quality Ge epitaxial layers on Si(100)
- 2003
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Ingår i: Japanese Journal of Applied Physics. - 0021-4922. ; 42:5B, s. 517-519
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Tidskriftsartikel (refereegranskat)abstract
- A method of growing high-quality epitaxial Ge layers on a Si(100) substrate is reported. In this method, a 0.8 mum Si0.1Ge0.9 layer was first grown. Due to the large lattice mismatch between this layer and the Si substrate, many dislocations form near the interface and in the lower part of the Si0.1Ge0.9 layer. A 0.8 mum Si0.05Ge0.95 layer and a 1.0 mum top Ge layer were subsequently grown on the Si0.1Ge0.9 layer. The formed interfaces of Si0.05Ge0.95/Si0.1Ge0.9 and Ge/Si0.05Ge0.95 can bend and terminate the upward-propagated dislocations very effectively. The in situ annealing process was also performed for each individual layer. Experimental results show that the dislocation density in the top Ge layer can be greatly reduced, and the surface is very smooth, while the total thickness of the structure is only 2.6 mum.
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| 10. |
- Mitsugi, F., et al.
(författare)
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Ferroelectric and colossal magnetoresistive properties of a PbZr1-xTixO3/La1-xSrxMnO3 heterostructure film
- 2000
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Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 39:9B, s. 5418-5420
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Tidskriftsartikel (refereegranskat)abstract
- We report the ferroelectric and magnetoresistive properties and crystallization of a PbZr0.52Ti0.48O3 (PZT)/La0.8Sr0.2MnO3 (LSMO) heterostructure film prepared by pulsed-laser deposition on a MgO(100) single crystal substrate. Ferroelectric properties such as the hysteresis loop and dielectric constant of the Au/PZT/LSMO capacitor were compared with those of the Au/PZT/YBa2Cu3O7-x, (YBCO) superconductor heterostructure film. The resistivity of the LSMO film was as low as that of the YBCO film at room temperature. The fabricated Au/PZT/LSMO capacitor had a remanent polarization of 29 muC/cm(2), a coercive field of 30 kV/cm and a dielectric constant of about 1000.
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| 11. |
- Miyamoto, Y, et al.
(författare)
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InP hot electron transistors with a buried metal gate
- 2003
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Ingår i: Japanese Journal of Applied Physics. - 0021-4922. ; 42:12, s. 7221-7226
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Tidskriftsartikel (refereegranskat)abstract
- To apply the ballistic nature of hot electrons, an InP hot electron transistor with a buried metal (BM-HET) is reported. In this device, carriers are extracted from the emitter by an attractive potential originating from an embedded metal grating, and they propagate through intrinsic semiconductor material only. A simple estimation shows a high cutoff frequency and low output conductance. The estimated highest cutoff frequency is approximately 1 THz. Fabricated devices show that the collector current increased with the gate bias. After extraction of the leakage cur-rent, a clear saturation of the collector current in common-emitter characteristics was confirmed and the possibility of BM-HET as a candidate for high-speed electron devices was demonstrated.
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| 12. |
- Paskov, Plamen, et al.
(författare)
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Excited-state magnetoluminescence of InAs/GaAs self-assembled quantum dots
- 2001
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Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 40:3B, s. 1998-2001
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Tidskriftsartikel (refereegranskat)abstract
- The magnetoluminescence of InAs/GaAs self-assembled quantum dots (QDs) is studied. Using different excitation intensities, the dots are tilled with up to 11-12 electron-hole pairs and the magnetic field evolution of the excited-state emissions is revealed. The magnetoluminescence spectra resemble very well the spectra of uncorrelated electro-hole pairs. A splitting of the states with a nonzero angular momentum quantum number is observed and the in-plane reduced electron-hole mass is determined. The experimental value is found to be in a good agreement with the theoretical predictions based on the eight-band k . p model including both strain effect and band nonparabolicity.
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| 13. |
- Paskov, Plamen, 1959-, et al.
(författare)
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Optical up-conversion processes in InAs quantum dots
- 2001
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Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 40:3 B, s. 2080-2083
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Tidskriftsartikel (refereegranskat)abstract
- Up-converted photoluminescence (UPL) in InAs/GaAs self-assembled quantum dots (QDs) is reported. With a resonant excitation of QDs we observe an efficient emission from the GaAs barrier. The excitation spectrum of the UPL shows that the signal disappears if the excitation energy is tuned below the absorption band of the QDs. The intensity of UPL exhibits an almost quadratic dependence on the excitation intensity. The observed effect is explained by a two-step two-photon absorption process involving quantum dot states as intermediate states. ⌐ 2001 The Japan Society of Applied Physics.
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| 14. |
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| 15. |
- Plaine, G. Y., et al.
(författare)
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Low-temperature metal-organic vapor-phase epitaxy growth and performance of 1.3-mu m GaInNAs/GaAs single quantum well lasers
- 2002
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Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 41:2B, s. 1040-1042
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Tidskriftsartikel (refereegranskat)abstract
- GaInNAs/GaAs quantum-well (Q V) lasers emitting at 1.3 mum. were grown using metal-organic vapor-phase epitaxy (MOVPE) in the limit of very low growth rate and temperature. The material was characterized by photoluminescence (PL) Spectroscopy as well as by implementation in broad-area (BA) edge-emitting lasers. While the PL intensity was found to decrease by more than two orders of magnitude between 1175 and 1350 mn, the corresponding BA laser threshold current showed a much more modest increase. For a 1.28-mum laser the threshold current was 1.2 kA/cm(2) (1200 pin long devices), with a slope efficiency 0.24 W/A per facet and T-0 = 100 K. Comparison between PL emission properties and BA laser performance revealed a complex relationship. A high PL intensity does not necessarily lead to low threshold-current lasers. In these cases, the FWHM seems to be the more relevant parameter for QW optimization.
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| 16. |
- Suda, Y., et al.
(författare)
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Characterization of crystalline TiC films grown by pulsed Nd : YAG laser deposition
- 2000
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Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 39:7B, s. 4575-4576
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Tidskriftsartikel (refereegranskat)abstract
- Titanium cal bide (TiC) thin films have been grown on Si (100) substrates using a pulsed neodymium: yttrium-aluminum-garnet (Nd:YAG) laser deposition method. X-ray diffraction (XRD) pattern of the TiC film shows that substrate temperature is one of the most important parameters in the fabrication of crystalline TiC film. Crystalline TiC films can be prepared at substrate temperatures above 500 degrees C. Field emission scanning electron microscope (FE-SEM) indicates that the surface of the film is very smooth and pinhole-free.
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| 17. |
- Takahashi, M., et al.
(författare)
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Oxygen annealing effect of photoelectron spectra in SrBi2Ta2O9 film
- 2002
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Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 41:11B, s. 6797-6802
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Tidskriftsartikel (refereegranskat)abstract
- Photoelectron spectra have been studied to clarify O-2-annealing effects on the band diagram of the metal-SrBi2Ta2O9 (SBT) junction and ionization energy of SBT films deposited by the pulsed laser, deposition (PLD) method. Photoemission spectra obtained by ultraviolet light irradiation have a threshold of 5.90 eV for the as-deposited SBT film and 5.56 eV for the O-2-annealed one. This shift of the threshold indicates that the annealing treatment has increased the Fermi level by 0.34 eV. On the assumption of a 4.2 eV band gap and 3.5 eV electron affinity for the SBT, as-deposited SBT has been estimated to give a 0.60 eV lower barrier height for holes than that for electrons, which is possibly because of, insufficiently oxidized (Bi2O2)(2+) layers as indicated by X-ray photoelectron spectroscopy (XPS). After annealing in O-2, however, barrier height energies for holes and electrons become closer to each other. These results agree with our previous studies which have reported that the O-2-annealing suppressed the leakage current through SBT and improved the retention characteristics of the metal-ferroelectric-insulator-semiconductor structure.
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| 18. |
- Takeyama, W, et al.
(författare)
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Structural investigation of the so-called Ca/Si(111)-(5 x 1) surface
- 2003
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Ingår i: Japanese Journal of Applied Physics. - : Institute of Physics (IOP). - 0021-4922 .- 1347-4065. ; 42, s. 4663-4666
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the geometric, structure of the so-called Ca/Si(111)-(5 x 1) surface using low-energy electron diffraction (LEED) and high-resolution core-level photoelectron spectroscopy. In LEED, dim extra spots besides the x 5 spots were observed after cooling the sample to 100 K. The positions of these dim spots reveal that this phase has a x 2 periodicity along its one-dimensional (ID) chains. In Si 2p core-level spectra, we observed five surface components. By considering the energy shift and intensity of each surface component and the 0.3ML Ca coverage, we propose a structural model of this surface.
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| 19. |
- Yeom, HW, et al.
(författare)
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High resolution photoemission study of low-temperature oxidation on the Si(001) surface
- 2000
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Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 39:7B, s. 4460-4463
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Tidskriftsartikel (refereegranskat)abstract
- High-resolution photoemission is applied to the oxygen adsorption on the Si(001) surface at 120 K and the subsequent evolution of the adsorbates upon annealing. Si 2p components due to the Si2+ and Si3+ species are observed from the very early stage of adsorption at similar to 120 K, which grow linearly with the oxygen coverage. This indicates an active agglomeration of oxygen adsorbates even for the submonolayer adsorption at low temperature. Annealing above 500 K enhances the agglomeration by mostly converting the Si1+ species into Si3+ and then into Si4+. In addition, the annealing changes the Si 2p binding energies for the Si2+ and Si3+ species by 0.14 and 0.23 eV, respectively. These shifts are attributed to the structural relaxation (strain relief) of the metastable oxygen-adsorbate complex formed at low temperature.
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| 20. |
- You, Lixing, 1976
(författare)
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Controlling the Intrinsic Josephson Junction Number in a Bi2Sr2CaCu2O8+δ Mesa
- 2004
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Ingår i: Japanese Journal of Applied Physics. - 1347-4065 .- 0021-4922. ; 43:7A, s. 4163-4165
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Tidskriftsartikel (refereegranskat)abstract
- In fabricating Bi2Sr2CaCu2O8+δ intrinsic Josephson junctions in 4-terminal mesa structures, we modify the conventionalfabrication process by markedly reducing the etching rates of argon ion milling. As a result, the junction number in a stack canbe controlled quite satisfactorily as long as we carefully adjust those factors such as the etching time and the thickness of theevaporated layers. The error in the junction number is within ±1. By additional ion etching if necessary, we can controllablydecrease the junction number to a rather small value, and even a single intrinsic Josephson junction can be produced.
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| 21. |
- Zhang, YW, et al.
(författare)
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Characterisation of compact discs using time of flight-energy elastic recoil detection analysis
- 2001
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Ingår i: JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS. - : INST PURE APPLIED PHYSICS. - 0021-4922. ; 40:2A, s. 629-633 Language: English
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Tidskriftsartikel (refereegranskat)abstract
- The challenge of meeting the ever increasing demands for low-cost information storage media with greater information storage density and rapid access has prompted development of sophisticated optical technologies, e.g., compact disc (CD) and digital video
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