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1.	Alekseev, A. Y., et al. (författare) Structural stability and electronic properties of 2D alkaline-earth metal silicides, germanides, and stannides 2020 Ingår i: Japanese Journal of Applied Physics. - : IOP PUBLISHING LTD. - 0021-4922 .- 1347-4065. ; 59 Forskningsöversikt (refereegranskat)abstract We present the results of an extended theoretical study of the structure, phonon, electronic and optical properties of 2D alkaline-earth metal silicides, germanides and stannides (2D Me2X, where Me=Mg, Ca, Sr, Ba and X=Si, Ge, Sn). The performed analysis has shown the occurrence of the pseudo passivation effect and ionic chemical bonding in these 2D Me2X. In addition, the preformed investigation of their phonon spectra has shown the absence of imaginary frequencies indicating the stability of these 2D structures. The band structure calculations performed using the hybrid functional have revealed that all 2D Me2X are semiconductors with the gap varying from 0.12 to 1.01 eV. Among them Mg- and Ca-based 2D materials are direct band-gap semiconductors with the first direct transition having appreciable oscillator strength. We also propose to consider ternary 2D silicides, germanides and stannides with different Me atoms as a feasible way to modify properties of parent 2D Me2X.
2.	Ben Sedrine, Nebiha, et al. (författare) Bandgap Engineering and Optical Constants of YxAl1-xN Alloys 2013 Ingår i: Japanese Journal of Applied Physics. - : Japan Society of Applied Physics. - 0021-4922 .- 1347-4065. ; 52:8 Tidskriftsartikel (refereegranskat)abstract We study wurtzite Yx Al1-xN (0 andlt;= x andlt;= 0:22) films with (0001) orientation deposited by magnetron sputtering epitaxy on Si(100) substrates and we determine the alloys band gap energies and optical constants. Room temperature spectroscopic ellipsometry (SE) is employed in the energy range from 1 to 6.3 eV, and data modeling based on the standard dielectric function model is used. As a result of the SE data analysis the Yx Al1-xN refractive index and extinction coefficient are determined. The band gap of Yx Al1-xN is found to decrease linearly from 6.2 eV (x=0) down to 4.5 eV (x=0:22). We further observe an increase of the refractive index with increasing Y content; from 1.93 to 2.20 (at 2 eV) for x=0 and 0.22, respectively, reflecting the increase in material density.
3.	Bengtsson, Stefan, 1961, et al. (författare) Applications of aluminium nitride films deposited by reactive sputtering to silicon-on-insulator materials 1996 Ingår i: Japanese Journal of Applied Physics. - 1347-4065 .- 0021-4922. ; 35:8R, s. 4175-4181 Tidskriftsartikel (refereegranskat)
4.	Bergsten, Johan, 1988, et al. (författare) AlGaN/GaN high electron mobility transistors with intentionally doped GaN buffer using propane as carbon precursor 2016 Ingår i: Japanese Journal of Applied Physics. - : IOP Publishing. - 1347-4065 .- 0021-4922. ; 55:5 Tidskriftsartikel (refereegranskat)abstract AlGaN/GaN high electron mobility transistors (HEMTs) fabricated on a heterostructure grown by metalorganic chemical vapor deposition using an alternative method of carbon (C) doping the buffer are characterized. C-doping is achieved by using propane as precursor, as compared to tuning the growth process parameters to control C-incorporation from the gallium precursor. This approach allows for optimization of the GaN growth conditions without compromising material quality to achieve semi-insulating properties. The HEMTs are evaluated in terms of isolation and dispersion. Good isolation with OFF-state currents of 2 x 10(-6)A/mu m, breakdown fields of 70V/mu m, and low drain induced barrier lowering of 0.13mV/V are found. Dispersive effects are examined using pulsed current-voltage measurements. Current collapse and knee walkout effects limit the maximum output power to 1.3W/mm. With further optimization of the C-doping profile and GaN material quality this method should offer a versatile approach to decrease dispersive effects in GaN HEMTs. (C) 2016 The Japan Society of Applied Physics
5.	Bergsten, Johan, et al. (författare) AlGaN/GaN high electron mobility transistors with intentionally doped GaN buffer using propane as carbon precursor 2016 Ingår i: Japanese Journal of Applied Physics. - : Institute of Physics Publishing (IOPP). - 0021-4922 .- 1347-4065. ; 55, s. 05FK02-1-05FK02-4 Tidskriftsartikel (refereegranskat)abstract AlGaN/GaN high electron mobility transistors (HEMTs) fabricated on a heterostructure grown by metalorganic chemical vapor deposition using analternative method of carbon (C) doping the buffer are characterized. C-doping is achieved by using propane as precursor, as compared to tuningthe growth process parameters to control C-incorporation from the gallium precursor. This approach allows for optimization of the GaN growthconditions without compromising material quality to achieve semi-insulating properties. The HEMTs are evaluated in terms of isolation anddispersion. Good isolation with OFF-state currents of 2 ' 10%6A/mm, breakdown fields of 70V/μm, and low drain induced barrier lowering of0.13mV/V are found. Dispersive effects are examined using pulsed current–voltage measurements. Current collapse and knee walkout effectslimit the maximum output power to 1.3W/mm. With further optimization of the C-doping profile and GaN material quality this method should offer aversatile approach to decrease dispersive effects in GaN HEMTs.
6.	Bunk, Richard, et al. (författare) Guiding molecular motors with nano-imprinted structures 2005 Ingår i: Japanese Journal of Applied Physics. - 0021-4922. ; 44:5A, s. 3337-3340 Tidskriftsartikel (refereegranskat)abstract This work, for the first time, demonstrates that nano-imprinted samples, with 100 nm wide polymer lines, can act as guides for molecular motors consisting of motor proteins actin and myosin. The motor protein function was characterized using fluorescence microscopy and compared to actomyosin motility on non-structured nitrocellulose surfaces. Our results open for further use of the nano-imprint technique in the production of disposable chips for bio-nanotechnological applications and miniaturized biological test systems. We discuss how the nano-imprinted motor protein assay system may be optimized and also how it compares to previously tested assay systems involving low-resolution UV-lithography and low throughput but high-resolution electron beam lithography.
7.	Deppert, Knut, et al. (författare) Aerosol fabrication of nanocrystals of InP 1999 Ingår i: Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers. - 0021-4922. ; 38:2 B, s. 1056-1059 Tidskriftsartikel (refereegranskat)abstract Nanocrystals of indium phosphide, with diameters of around 10nm, have been produced via an aerosol route. The method is based on the formation of monodisperse indium droplets and the subsequent reaction with phosphine at elevated temperature. The size of the final InP nanocrystal is self-limited by the size of the introduced size-selected In droplet. This size can be tuned carefully, thus this method allows a narrow size distribution of the nanocrystals. The kinetics of the reaction of In to produce InP depends on the temperature and the phosphine flow. Extensive high resolution transmission electron microscopy studies lead to a consistent picture of the process. Our approach opens the possibility for efficient production of size-selected semiconductor nanocrystals and it will allow new types of self-assembly and control of quantum dots.
8.	Dutta, Joydeep, et al. (författare) Effect of Ion Bombardment on the Properties of Hydrogenated Amorphous Silicon Prepared from Undiluted and Xenon-Diluted Silane 1992 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 31:3B, s. L299-L302 Tidskriftsartikel (refereegranskat)abstract The contribution of ion bombardment to the growth of hydrogenated amorphous silicon prepared by plasma-enhanced chemical vapour deposition from silane and xenon-diluted silane source gases was studied by applying an external d.c. voltage to the substrate electrode. The role played by the xenon ions in the growth of the materials prepared from xenon-diluted silane source gas has been considered. It is demonstrated that the xenon ions are responsible for the growth of the materials showing stable photoconductivity behaviour under light illumination.
9.	Edholm, Bengt, et al. (författare) Transient Measurements of Heat Distribution in Devices Fabricated on Silicon-On Diamond Material 1995 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 34:9A, s. 4706-4714 Tidskriftsartikel (refereegranskat)abstract Thermal properties of devices fabricated on different silicon-on-diamond (SOD) and silicon-on-insulator (SOI) structures have been investigated. A new method for transient measurements of temperature distributions in the S OI/S OD materials has been devel
10.	Elamain, Omaima Abubakr, et al. (författare) Polar flexoelectric in-plane and out-of-plane switching in bent core nematic mixtures 2016 Ingår i: Japanese Journal of Applied Physics. - : IOP Publishing. - 0021-4922 .- 1347-4065. ; 55:7 Tidskriftsartikel (refereegranskat)abstract Polar electro-optic response, arising from the coupling between an applied in-plane and out-of-plane dc electric field, respectively, and the flexoelectric polarization of bent core nematic liquid crystal mixtures with hybrid alignment is studied in conventional sandwich cells with homeotropic anchoring at one of the cell substrates and planar at the other. Such a hybrid alignment, however, results in a splay/bend elastic deformation of the nematic giving rise of a flexoelectric polarization. It was found that a pronounced polar electro-optic response, both in-plane and out of plane, took place in the bent core nematic mixtures at very low voltages due to the high flexoelectric polarization in these mixtures, compared with the one observed in calamitic liquid crystals.
11.	Frantti, J, et al. (författare) Neutron diffraction studies of Pb(ZrxTi1-x)O-3 ceramics 2000 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 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,
12.	Furusho, Hirotoshi, et al. (författare) Lipid Nanotube Encapsulating Method in Low-Energy Scanning Transmission Electron Microscopy Analyses 2009 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 48, s. -097001 Tidskriftsartikel (refereegranskat)abstract The lipid nanotube (LNT) encapsulating method is a rational sample fixation method that can be used to mount samples for transmission electron microscopy analyses. By employing the LNT encapsulating method in 30 kV low-voltage scanning transmission electron microscopy (LV-STEM), it is possible to record multiangle images of ferritin without using the negative staining method. We have also recorded a tilted series of high-contrast LV-STEM images and reconstructed three-dimensional images. These results show that LNTs have sufficient durability for LV electron beam, and indicate the potential of the LNT encapsulating method as a sample fixation method of LV electron microscopy
13.	Gogova, Daniela, 1967-, et al. (författare) High-quality 2? bulk-like free-standing GaN grown by HydrideVapour phase epitaxy on a Si-doped metal organic vapour phase epitaxial GaN template with an ultra low dislocation density 2005 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 44:3, s. 1181-1185 Tidskriftsartikel (refereegranskat)abstract High-quality 2? crack-free free-standing GaN has been attained by hydride vapour phase epitaxial growth on a Si-doped MOVPE GaN template with a low dislocation density and subsequent laser-induced lift-off process. A low value of dislocation density of ~2.0 × 107cm-2 on the Ga-polar face was determined from cathodoluminescence images. X-ray diffraction (XRD) and low-temperature photoluminescence (PL) were exploited to investigate the structural and optical properties of the GaN material. The full width at half maximum value of XRD ?-scan of the free-standing GaN is 248 arcsec for the (1 0 1 4) reflection. The XRD and low-temperature PL mapping measurements consistently proved the high crystalline quality as well as the lateral homogeneity and the small residual stress of the material. Hence, the bulk-like free-standing GaN studied here is highly advantageous for being used as a lattice-constant and thermal-expansion-coefficient matched substrate for additional strain-free homoepitaxy of III-nitrides-based device heterostructures. The strain-free homoepitaxy will significantly reduce the defect density and thus, an improvement of the device performance and lifetime could be achieved. © 2005 The Japan Society of Applied Physics.
14.	Gogova, Daniela, et al. (författare) Optical and structural characteristics of virtually unstrained bulk-like GaN 2004 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 43:4A, s. 1264-1268 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.
15.	Grivickas, V., et al. (författare) Characterization of Si Wafer Bonding by Injection-Dependent Recombination Velocity 1995 Ingår i: Japanese Journal of Applied Physics, Part 2: Letters. - 0021-4922. ; 34, s. L806-L809 Tidskriftsartikel (refereegranskat)
16.	Hammar, M., et al. (författare) Systematics of electrical conductivity across InP to GaAs wafer-fused interfaces 1999 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 38:2 B, s. 1111-1114 Tidskriftsartikel (refereegranskat)abstract We report on the electrical and compositional characterization of wafer-fused isotype heterojunctions between Zn-, C- or Si-doped GaAs and Zn- or Si-doped InP. The junctions were characterized by current-voltage and secondary ion mass spectrometry (SIMS) measurements. It is demonstrated that very low-resistive junctions can be obtained in each case, but also that there is a strong influence from the detailed sample structure and processing conditions. SIMS was used to monitor the doping concentration across the interface as well as the impurity concentrations of oxygen, carbon and iron. Â© 1999 Publication Board, Japanese Journal of Applied Physics.
17.	Hashemi, Seyed Ehsan, 1986, et al. (författare) Engineering the Lateral Optical Guiding in Gallium Nitride (GaN)-based Vertical-Cavity Surface-Emitting Laser (VCSEL) Cavities to Reach the Lowest Threshold Gain 2013 Ingår i: Japanese Journal of Applied Physics. - 1347-4065 .- 0021-4922. ; 52:8 PART 2, s. 08JG04 - Tidskriftsartikel (refereegranskat)abstract In order to improve the current injection in GaN-based blue vertical-cavity surface-emitting lasers (VCSELs) a dielectric aperture is generally used in combination with an indium–tin-oxide (ITO) layer on the top intracavity p-contact layer. The most straightforward way to realize this introduces a depression of the structure near the optical axis and we show, by using a two-dimensional (2D) effective index method and a three-dimensional (3D) coupled-cavity beam propagation method, that this typically results in optically anti-guided structures with associated high optical losses and thus very high threshold gains. Remarkably, the threshold gain reduces with increased negative guiding, which is due to improved lateral confinement and reduction of lateral leakage. Still, moderately positively guided designs should be preferred to avoid the detrimental effect of lateral leakage and high diffraction loss. To ensure positive index guiding, we propose to planarize the structure or introduce an elevation near the optical axis by additional processing, with an associated reduction in threshold material gain from 6000 to 2000 cm-1 for the studied structures.
18.	Hatayama, Tomoaki, et al. (författare) Low-temperature photoluminescence of 8H-SiC homoepitaxial layer 2016 Ingår i: Japanese Journal of Applied Physics. - : IOP PUBLISHING LTD. - 0021-4922 .- 1347-4065. ; 55:2, s. 020303- Tidskriftsartikel (refereegranskat)abstract Low-temperature photoluminescence of a nitrogen-doped 8H-SiC epilayer homoepitaxially grown by a chemical vapor deposition method is reported. The polytype and stacking sequence of the epilayers were confirmed by transmission electron microscopy analyses. The identification of emission lines is discussed in terms of the temperature dependence of the luminescence spectra. Luminescence related to the free excitons and the nitrogen-bound excitons is observed, which allows the determination of the excitonic bandgap of the 8H-SiC polytype. In addition, the low binding energies found for the nitrogen-bound excitons imply shallow levels for the nitrogen donors. (C) 2016 The Japan Society of Applied Physics
19.	Hedberg, Claes, et al. (författare) Design Alterations of a High Power Air Transducer 2007 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 46:7, s. 4908-4911 Tidskriftsartikel (refereegranskat)abstract For certain resonant high-power air transducers exists a radiating cone which is in some way connected to a forcing piezoelectric ceramic. This study focuses purely on the cone structure itself, and the form of excitation that gives desired results on the vibration modes of the cone. In the new design three different parameters are changed from existing devices. They are: 1) the change of the round piezoelectric disc center position to a piezoelectric ring shape, while making the cone center fixed, 2) the cutting of the cone into leaves, and 3) the radial thickness decreasing with radius. In simulations, the new design yields considerably higher vibration amplitudes.
20.	Henry, Anne, et al. (författare) Early stages of growth and crystal structure evolution of boron nitride thin films 2016 Ingår i: Japanese Journal of Applied Physics. - : IOP PUBLISHING LTD. - 0021-4922 .- 1347-4065. ; 55:5, s. 05FD06- Tidskriftsartikel (refereegranskat)abstract A study of the nucleation and crystal structure evolution at the early stages of the growth of sp(2)-BN thin films on 6H-SiC and alpha-Al2O3 substrates is presented. The growth is performed at low pressure and high temperature in a hot wall CVD reactor, using ammonia and triethylboron as precursors, and H-2 as carrier gas. From high-resolution transmission electron microscopy and X-ray thin film diffraction measurements we observe that polytype pure rhombohedral BN (r-BN) is obtained on 6H-SiC substrates. On alpha-Al2O3 an AlN buffer obtained by nitridation is needed to promote the growth of hexagonal BN (h-BN) to a thickness of around 4 nm followed by a transition to r-BN growth. In addition, when r-BN is obtained, triangular features show up in plan-view scanning electron microscopy which are not seen on thin h-BN layers. The formation of BN after already one minute of growth is confirmed by X-ray photoelectron spectroscopy. (C) 2016 The Japan Society of Applied Physics
21.	Hirasaki, Takahide, et al. (författare) Investigation of NH3 input partial pressure for N-polarity InGaN growth on GaN substrates by tri-halide vapor phase epitaxy 2016 Ingår i: Japanese Journal of Applied Physics. - : IOP PUBLISHING LTD. - 0021-4922 .- 1347-4065. ; 55:5, s. 05FA01- Tidskriftsartikel (refereegranskat)abstract The influence of NH3 input partial pressure on N-polarity InGaN grown by tri-halide vapor phase epitaxy was investigated. It was found that surface morphology, solid composition and optical properties were affected by NH3 input partial pressure. As shown in thermodynamic analyses, the indium content increased due to an increase in the driving force for InN deposition caused by increased NH3 input partial pressure. In addition, the deep level emission around 2.1 eV in photoluminescence measurements drastically decreased at higher NH3 input partial pressures. Ab initio calculations and subsequent secondary ion mass spectrometry measurements suggested the reduction of metal-vacancies and/or carbon impurity incorporation in the InGaN layers. (C) 2016 The Japan Society of Applied Physics
22.	Hirohashi, Junji, et al. (författare) Embryonic nucleation method for fabrication of uniform periodically poled structures in potassium niobate for wavelength conversion devices 2004 Ingår i: Japanese journal of applied physics. - 0021-4922. ; 43:2, s. 559-566 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.
23.	Hirohashi, Junji, et al. (författare) Total refraction of p-polarized light at the 90-degree domain boundary in the ferroelectric crystal 2004 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 43:6A, s. 3413-3418 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.)
24.	Huang, Tongde, 1985, et al. (författare) A power detector based on GaN high-electron-mobility transistors for a gigabit on–off keying demodulator at 90 GHz 2019 Ingår i: Japanese Journal of Applied Physics. - : IOP Publishing. - 1347-4065 .- 0021-4922. ; 58:SC Tidskriftsartikel (refereegranskat)
25.	Illarionov, Y.Yu., et al. (författare) Bias-temperature instability on the back gate of single-layer double-gated graphene field-effect transistors 2016 Ingår i: Japanese Journal of Applied Physics. - : Institute of Physics (IOP). - 0021-4922 .- 1347-4065. ; 55:4 Tidskriftsartikel (refereegranskat)abstract We study the positive and negative bias-temperature instabilities (PBTI and NBTI) on the back gate of single-layer double-gated graphene fieldeffect transistors (GFETs). By analyzing the resulting degradation at different stress times and oxide fields we show that there is a significant asymmetry between PBTI and NBTI with respect to their dependences on these parameters. Finally, we compare the results obtained on the high-k top gate and SiO2 back gate of the same device and show that SiO2 gate is more stable with respect to BTI.
26.	Imura, M, et al. (författare) 3-D flow visualization for construction of the model of the blood flow in the heart 2000 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 39:5 B, s. 3246-3251 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.
27.	Inoue, K, et al. (författare) Angular dependence of Al-2p X-ray yield spectra of GaAs/AlAs/GaAs heterostructures 1999 Ingår i: JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS. - : JAPAN J APPLIED PHYSICS. - 0021-4922. ; 38, s. 572-575 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract The X-ray emission yield by the Al-2p core-exciton excitation in GaAs/AlAs/GaAs heterostructures is studied theoretically: especially the angular correlation between absorbed and emitted X-rays are discussed. It becomes clear that the angular dependence o
28.	Isaev, Eyvas, et al. (författare) Ab initio Calculations of Elastic Constants of Superalloys 2011 Ingår i: JAPANESE JOURNAL OF APPLIED PHYSICS. - : Japan Society of Applied Physics / Japanese Journal of Applied Physics; 1999. - 0021-4922. ; 50:5 Tidskriftsartikel (refereegranskat)abstract Using the-state-of-the-art ab initio method we have studied elastic constants of alloys potentially interesting for high temperature applications. We have shown that Cr substitutes the Al sublattice in B2 NiAl at concentration up to 40 at. %, but at higher Cr content it prefers the Ni-sublattice. Alloying of NiAl with Cr yields reduced strength but improves the ductility of the alloys. Alloying of NiAl with W which substitutes the Al sublattice, leads to a strong decrease of the shear modulus, and near 50 at.% of W the alloy becomes mechanically unstable as elastic constant C is negative. This is in agreement with our phonon calculations where we found soft modes along the [110] direction for B2 NiW. According to our calculations in (Ru,Ni)Al alloys the shear modulus is almost constant up to 40 at.% of Ni, at higher Ni concentrations it is drastically reduced. We have shown that the changes in elastic properties of (Ru-X)Al alloys are due to electronic topological transitions.
29.	Isaeva, Leyla, et al. (författare) Ab initio Phonons in Magnetic Ni2MnAl 2011 Ingår i: Japanese Journal of Applied Physics. - : Japan Society of Applied Physics / Japanese Journal of Applied Physics; 1999. - 0021-4922 .- 1347-4065. ; 50:5, s. 05FE07- Tidskriftsartikel (refereegranskat)abstract In the present work we report the results of ab initio studies of electronic and dynamic properties of nickel based Heusler alloy Ni2MnAl. The total magnetic moment and elastic constants were also evaluated and compared to experimental results where possible. We found that the phonon dispersion relations calculated in this work within the linear response method did not reveal any softening of the transversal acoustic mode TA(2) along [xi, xi, 0] direction in accordance with the experiment and in controversy to previous theoretical studies.
30.	Ishio, H (författare) Composition of quantum ratchets with chaotic dots 2001 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 40:6A, s. 4269-4271 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.
31.	Ive, Tommy, 1968, et al. (författare) Design and Fabrication of AlN/GaN Heterostructures for Intersubband Technology 2012 Ingår i: Japanese Journal of Applied Physics. - 1347-4065 .- 0021-4922. ; 51:1, s. Article Number: 01AG07 - Tidskriftsartikel (refereegranskat)abstract We have used models based on the effective-mass approximation and Schrodinger-Poisson to design AlN/GaN multiple quantum well structures for intersubband transitions between two or three energy levels. The structures were realized by molecular beam epitaxy and the surface morphology and structural quality were investigated. We also investigated GaN waveguides that were fabricated using standard cleanroom techniques. Our work is focused on the various challenges associated to the fabrication of quantum cascade lasers based on group III-nitrides. These challenges are discussed in the light of our results.
32.	Jepsen, O., et al. (författare) Electronic Structure and Photoemission Spectra of Cu Compounds 1993 Ingår i: Japanese Journal of Applied Physics. - : Institute of Physics Publishing (IOPP). - 0021-4922 .- 1347-4065. ; 32:S3, s. 212-216 Tidskriftsartikel (refereegranskat)
33.	Jönsson, Stina, et al. (författare) Photoelectron spectroscopy of the contact between the cathode and the active layers in plastic solar cells : the role of LiF 2005 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 44:6A, s. 3695-3701 Tidskriftsartikel (refereegranskat)abstract The surfaces and electrode interfaces of a polymer blend used in prototype solar cells have been characterized with photoelectron spectroscopy. The polymer blend in question is a 1:4 mixture of APFO-3:PCBM. Based on surface analysis of the pristine film we can conclude that the surface of the blend is a 1:1 mixture of APFO-3 and PCBM. The electrode systems studied are the widely used Al and Al/LiF contacts. LiF prevents formation at the Al/organic interface of Al-organic complexes that destroy the π-conjugation. In addition to this, there are two other beneficial, thickness dependent, effects. Decomposition of LiF occurs for thin enough layers in which the LiF species are in contact with both the organic film and the Al atoms, which creates a low workfunction contact. For thicker (multi)layers, the dipole formed at the LiF/organic interface is retained as no decomposition of the LiF occurs upon Al deposition.
34.	Kalaboukhov, Alexei, 1975, et al. (författare) Inhomogeneous Microstructure and Electrical Transport Properties at the LaAlO3/SrTiO3 Interface 2012 Ingår i: Japanese Journal of Applied Physics. - 1347-4065 .- 0021-4922. ; 51:11(spec.issue), s. article no. 11PG10 - Tidskriftsartikel (refereegranskat)abstract Medium-energy ion spectroscopy (MEIS), scanning transmission electron microscopy (STEM) and X-ray photoemission spectroscopy (XPS) were used to investigate the composition and microstructure of LaAlO3/SrTiO3 (LAO/STO) interfaces grown by pulsed laser deposition of LAO on TiO2-terminated STO substrates under different oxidizing conditions. MEIS and XPS indicated Sr/La and Al/Ti intermixing within several atomic layers at all studied interfaces. XPS and STEM revealed that La diffuses deeper than Al. Analysis of the MEIS data suggests inhomogeneous lateral distribution of the diffused elements. This is further supported by the observation of a large positive magneto-resistance at low temperatures. We discuss the role of lateral inhomogeneities on the formation of the electron gas at the LAO/STO interface.
35.	Keiper, D., et al. (författare) 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 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 39:11, s. 6162-6165 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.
36.	Kim, Tae Kyung, et al. (författare) Fabrication of Microfluidic Platform with Optimized Fluidic Network toward On-Chip Parallel Systematic Evolution of Ligands by Exponential Enrichment Process 2011 Ingår i: Japanese Journal of Applied Physics. - 0021-4922. ; 50:6, s. 05-06 Tidskriftsartikel (refereegranskat)abstract This paper presents the design and fabrication of a microplatform with the optimal fluidic network for an on-chip parallel "systematic evolution of ligands by exponential enrichment" (SELEX) process. The effectiveness of the optimized fluidic network for on-chip five-plex aptamer screening was verified by measuring the airflow rate at the elution ports and visualizing the specific elution during the SELEX process. The proposed device with an optimally designed hydraulic resistance-balanced channel network could be feasible and utilized as a multiplex selection module for a parallel SELEX process. (c) 2011 The Japan Society of Applied Physics
37.	Kobayashi, Takane, et al. (författare) Ion-stimulated desorption in the medium-energy regime 2014 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 53:6, s. 060305- Tidskriftsartikel (refereegranskat)abstract Ion-stimulated desorption in the medium-energy regime is investigated using a hydrogen rich Li2O sample. The desorbed yield dependencies for H+ and Li+ on incident ion species H-1(+) and He-4(+) in a medium energy regime are measured. For the mechanism of desorption it is considered that an inner shell electron vacancy is generated in oxygen atoms of the target by the ion impact. This inner shell vacant state is then filled by Auger transition of an electron from surrounding H or Li atoms. The resulting coulomb repulsion between H+ or Li+ and O+ leads to ejection of H+ or Li+ from the surface.
38.	Koh, J. H., et al. (författare) Dielectric relaxation behavior of Ag(Ta,Nb)O-3 interdigital capacitors on oxide substrates 2004 Ingår i: Japanese Journal of Applied Physics. - : IOP Publishing. - 0021-4922 .- 1347-4065. ; 43:4A, s. 1434-1437 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.
39.	Li, Xin, et al. (författare) Re-writable multi-domain liquid crystal alignment layers through laser-induced micropatterning 2006 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 45:20-23, s. L591-L594 Tidskriftsartikel (refereegranskat)abstract We report a method for the preparation of multi-domain liquid crystal (LC) alignment layers on polyimide surfaces with laser-induced periodic surface structures. Atomic force microscopy confirmed that the laser-induced microstructures could be easily erased and re-constructed by repeated laser exposure. The microstructures demonstrated excellent abilities to align LCs in a multi-domain way. The intricate micropatterning of LCs with high resolution was obtained. The opto-electric properties of the LC cells were also determined. In addition, the method is available to a wide range of polymeric substrates, including flexible ones such as poly(ethylene terephthalate).
40.	Luo, GL, et al. (författare) Growth of high-quality Ge epitaxial layers on Si(100) 2003 Ingår i: Japanese Journal of Applied Physics. - 0021-4922. ; 42:5B, s. 517-519 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.
41.	Masuda, Rui, et al. (författare) Improvements in Optical Properties of (0001) ZnO Layers Grown on (0001) Sapphire Substrates by Halide Vapor Phase Epitaxy Using Thick Buffer Layers 2012 Ingår i: Japanese Journal of Applied Physics. - : Japan Society of Applied Physics. - 0021-4922 .- 1347-4065. ; 51:3, s. 031103- Tidskriftsartikel (refereegranskat)abstract The optical properties of (0001) ZnO layers grown at 1000 degrees C on (0001) sapphire substrates by halide vapor phase epitaxy (HVPE) were investigated by various photoluminescence (PL) measurements. A layer grown with a H2O/ZnCl2 (VI/II) ratio of 20 on a 0.4-mu m-thick buffer layer exhibited a significant near-band-edge (NBE) peak blueshift and degraded internal quantum efficiency (eta(int)) due to residual compressive stress. Growth with a VI/II ratio of 600 diminished the NBE peak blueshift; however, deep level emission and a reduction of PL decay time (tau(PL)) were caused by point defects generated by excess O source supply. A layer without the NBE peak blueshift and deep level emission was realized by growth with a VI/II ratio of 20 and a buffer layer of 0.8 mu m. The eta(int) and tau(PL) for HVPE-grown layers could be improved to 4.1% and 122.8 ps by using the thick buffer layer and appropriate VI/II ratio.
42.	Mitsugi, F., et al. (författare) Ferroelectric and colossal magnetoresistive properties of a PbZr1-xTixO3/La1-xSrxMnO3 heterostructure film 2000 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 39:9B, s. 5418-5420 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.
43.	Miyamoto, Y, et al. (författare) InP hot electron transistors with a buried metal gate 2003 Ingår i: Japanese Journal of Applied Physics. - 0021-4922. ; 42:12, s. 7221-7226 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.
44.	Monemar, Bo, et al. (författare) Luminescence of Acceptors in Mg-Doped GaN 2013 Ingår i: Japanese Journal of Applied Physics. - : Japan Society of Applied Physics. - 0021-4922 .- 1347-4065. ; 52:8 Tidskriftsartikel (refereegranskat)abstract Recent photoluminescence (PL) data for Mg-doped GaN at 2 K are discussed, with reference to published theoretical calculations of the electronic level structure. It is concluded that the typical PL peaks at 3.466 eV (acceptor bound exciton ABE1) and the broader 3.27 eV donor-acceptor pair (DAP) PL are the expected standard PL signatures of the substitutional Mg acceptor. Additional broader peaks at 3.455 eV (ABE2) and 3.1 eV are suggested to be related to the same acceptors perturbed by nearby basal plane stacking faults. The low temperature metastability of PL spectra is assigned to a nonradiative metastable deep level.
45.	Mozumi, Michiya, et al. (författare) Anti-Aliasing method for ultrasonic 2D phase-sensitive motion estimator 2020 Ingår i: Japanese Journal of Applied Physics. - : IOP Publishing. - 0021-4922 .- 1347-4065. ; 59:SK Tidskriftsartikel (refereegranskat)abstract A 2D motion estimator can estimate tissue motions and blood flow dynamics more accurately than a 1D motion estimator. In this study, we proposed a simple anti-Aliasing filter to unwrap the phase of the cross spectrum. The proposed method is evaluated by simulation mimicking steady flows, and the magnitude of the true velocity was changed from 200 to 2400 mm s-1. In the simulation, bias error was improved from 295.0% to 4.9% by the proposed method at a true velocity magnitude of 1600 mm s-1. Also, in the in vivo measurement of the left ventricle, the wrapping in the phase of the cross spectrum was corrected by the proposed method, and the directions of the blood velocity vectors were estimated more accurately.
46.	Mozumi, Michiya, et al. (författare) Impact of spacing of ultrasound receiving beams on estimation of 2D motion velocity 2021 Ingår i: Japanese Journal of Applied Physics. - : IOP Publishing. - 0021-4922 .- 1347-4065. ; 60:SD Tidskriftsartikel (refereegranskat)abstract For more detailed measurement of cardiovascular motion and complex blood flow, a two-dimensional (2D) velocity estimation method is required in functional ultrasound imaging. The block matching method based on the correlation function is one of the standard 2D motion estimators. In this study, we investigated the effect of lateral sampling intervals of an ultrasonic B-mode image on the accuracy in velocity estimation. In simulation, bias error (BE) in estimated velocities became -13% with an ultrasonic center frequency of 7.5 MHz and spacings of receiving beams of 0.2 mm. Such a BE was improved from -13% to -1.4% by changing the spacings from 0.2 to 0.1 mm. In the in vivo experiment, the maximum velocity obtained with spacings of 0.2 mm was underestimated by -16% as compared to those obtained with 0.1 mm. Hence, the trend was similar to that in the simulation.
47.	Murdey, Richard J., et al. (författare) Charge injection barrier heights across multilayer organic thin films 2005 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 44:6 A, s. 3751-3756 Tidskriftsartikel (refereegranskat)abstract Organic multilayer structures having a tetrathiafulvalene (TTF) or tetracyanoquinodimethane (TCNQ) interlayer were grown by physical vapor deposition on gold, indium tin oxide (ITO) or poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) PEDOT-PSS, substrates chosen to be representative of the anode materials typically used in the manufacture of organic electronic devices. The top layer was either p-quarterphenyl (Qp) or the hole transport material N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine (TPD). The valence electronic structure and vacuum level of the compound interface were monitored as a function of film thickness by ultraviolet photoelectron spectroscopy (UPS). Here we report the dependence of the energy level alignment on the substrate work function and discuss how an organic interlayer having a strong electron accepting or donating characteristic might be used to control the charge injection from a conducting electrode to a semiconducting organic hole transport material. © 2005 The Japan Society of Applied Physics.
48.	Nagaoka, Ryo, et al. (författare) Basic study on estimation method of wall shear stress in common carotid artery using blood flow imaging 2020 Ingår i: Japanese Journal of Applied Physics. - : IOP Publishing. - 0021-4922 .- 1347-4065. ; 59 Tidskriftsartikel (refereegranskat)abstract In this paper, we propose a method for adaptive selection of the kernel size used in estimation of the wall shear stress (WSS) based on flow velocity profiles obtained by the blood flow imaging method based on enhancement of RF echo signals from blood cells using a singular value decomposition based clutter filter. Two simulation phantom experiments with the Field II program were performed to validate the proposed method. In the simulation experiments, the average bias error (BE) between the WSSs estimated by the conventional method and theoretical one was 16.5%. The proposed method could reduce the average BE to 12.3%. Also, the proposed method was applied to RF echo signals from a common carotid artery (CCA) of a healthy male subject. The WSSs in the CCA were estimated during one cardiac cycle and in a range similar to that in previous reports.
49.	Park, Jiho, et al. (författare) Spin-Conserving Tunneling of Excitons in Diluted Magnetic Semiconductor Double Quantum Wells 2008 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 47, s. 3533-3536 Tidskriftsartikel (refereegranskat)abstract Spin polarization in carrier tunneling was studied in double quantum wells by the polarized photoluminescence-excitation spectroscopy. The double quantum wells consist of a diluted magnetic quantum well of Zn0.77Cd0.15Mn0.08Se and a nonmagnetic quantum well of Zn0.82Cd0.18Se. Efficient spin-conserving tunneling of an exciton as an entity was observed from the nonmagnetic quantum well to the magnetic well. The spin-reversing tunneling was suppressed by two orders of magnitude in high magnetic field. The spin-conserving tunneling time was determined as 20 ps by time resolved photoluminescence measurement.
50.	Paskov, Plamen, et al. (författare) Excited-state magnetoluminescence of InAs/GaAs self-assembled quantum dots 2001 Ingår i: Japanese Journal of Applied Physics. - 0021-4922 .- 1347-4065. ; 40:3B, s. 1998-2001 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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