SwePub - search: L773:1882 0778

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1.	Fülöp, Attila, 1988, et al. (author) Phase transition of bismuth telluride thin films grown by MBE 2014 In: Applied Physics Express. - 1882-0786 .- 1882-0778. ; 7:4, s. Art. no. 045503- Journal article (peer-reviewed)abstract A previously unreported phase transition between Bi2Te3 and Bi4Te3 in bismuth telluride grown by molecular beam epitaxy is recorded via XRD, AFM, and SIMS observations. This transition is found to be related to the Te/Bi beam equivalent pressure (BEP) ratio. BEP ratios below 17 favor the formation of Bi4Te3 while Bi2Te3 is formed at higher ratios. Transport measurements reveal that Bi2Te3 has higher electron mobility than Bi4Te3.
2.	Hashemi, Seyed Ehsan, 1986, et al. (author) Effect of compositional interlayers on the vertical electrical conductivity of Si-doped AlN/GaN distributed Bragg reflectors grown on SiC'' 2017 In: Applied Physics Express. - 1882-0786 .- 1882-0778. ; 10:5, s. 055501- Journal article (peer-reviewed)abstract We have investigated the effect of strain-compensating interlayers on the vertical electrical conductivity of Si-doped AlN/GaN distributed Bragg reflectors (DBRs). Samples with 10.5 mirror pairs were grown through plasma-assisted molecular beam epitaxy on SiC. Room-temperature current–voltage characteristics were measured vertically in mesas through 8 of the 10.5 pairs. The sample with no interlayers yields a mean specific series resistance of 0.044 Ω cm2 at low current densities, while three samples with 5/5-Å-thick, 2/2-nm-thick, and graded interlayers have resistivities between 0.16 and 0.34 Ω cm2. Thus, interlayers impair vertical current transport, and they must be designed carefully when developing conductive DBRs.
3.	Huang, Dan, et al. (author) Ideal half-filled intermediate band position in CuGaS 2 generated by Sb-related defect complex: A first-principles study 2019 In: Applied Physics Express. - : IOP Publishing. - 1882-0786 .- 1882-0778. ; 12:2 Journal article (peer-reviewed)abstract Cu-based chalcopyrite compounds have attracted much attention for photovoltaic application, while some of them (like CuGaS 2 ) have energy gaps greater than the optimal value. An isolated and half-filled intermediate band located at the lower part of its original band gap exhibits in CuGaS 2 with (Sb Ga + Zn Ga ) or (Sb Ga + V Cu ) defect complex, in line with the intrinsic p-type conductivity of the host, revealed from our first-principles calculations. Subsequently, the absorption coefficients of CuGaS 2 can cover the full solar light spectrum efficiently. Based on the defect formation energy calculations, however, these defect complexes are hard to reach a large concentration under equilibrium condition. Nevertheless, non-equilibrium growth methods are suggested to prepare samples inheriting the excellent adsorption coefficients.
4.	Okujima, Masahiro, et al. (author) Molecular beam epitaxial growth of GaAs/GaNAsBi core-multishell nanowires 2021 In: APPLIED PHYSICS EXPRESS. - : IOP Publishing Ltd. - 1882-0778 .- 1882-0786. ; 14:11 Journal article (peer-reviewed)abstract GaAs/GaNAsBi/GaAs core-multishell nanowires were grown using molecular beam epitaxy on Si(111) substrates. The formation of the 20 nm wide GaNAsBi shell with a regular hexagonal structure was observed. The shell is estimated to contain approximately 1.5% N and 2.6% Bi and has a compressive lattice mismatch of less than 0.2% with GaAs layers. The strain mediation by the introduction of both N and Bi suppresses the crystalline deformation, resulting in the clear formation of the GaNAsBi shell. Thus, we obtained room-temperature photoluminescence with the maximum position at approximately 1300 nm from the GaAs/GaNAsBi/GaAs core-multishell nanowires.
5.	Tsutsumi, Rikuo, et al. (author) Outermost AlGaO(x)native oxide as a protection layer for GaAs/AlGaAs core-multishell nanowires 2020 In: APPLIED PHYSICS EXPRESS. - : IOP PUBLISHING LTD. - 1882-0778 .- 1882-0786. ; 13:7 Journal article (peer-reviewed)abstract We propose native oxide AlGaO(x)outer protective layer for GaAs/AlGaAs core-multishell nanowires to provide yearly stable stronger optical and electrical confinement within the nanowire core. We prepared core-multishell NWs consisting of GaAs core, Al0.2Ga0.8As multi-layered barrier layer, and amorphous Al(0.9)Ga(0.1)O(x)outer shell, which was obtained simply by growing Al-rich AlGaAs and exposing the NWs to the ambient air. Photoluminescence from the NWs reveals that the Al(0.9)Ga(0.1)O(x)outer shell provides efficient optical confinement and creates a compressive strain in the interior of the NW that enhances and blueshifts the photoluminescence of the GaAs core.
6.	Wang, P., et al. (author) Heteroepitaxy growth of GaAsBi on Ge(100) substrate by gas source molecular beam epitaxy 2016 In: Applied Physics Express. - : IOP Publishing. - 1882-0786 .- 1882-0778. ; 9:4 Journal article (peer-reviewed)abstract We have investigated the growth of GaAsBi single-crystal film on Ge substrate by gas source molecular beam epitaxy. A high-quality GaAsBi epilayer has been obtained. It has been found that the surfactant effect of Bi suppresses the interdiffusion of Ge at the GaAsBi/Ge interface and reduces the misfit dislocation density. The Bi atoms occupy the As sites, as indicated by the appearance of GaBi-like TO(G) and LO(G) phonon modes in Raman spectra. In addition, the redshift of the GaAs-like LO(G) phonon frequency has been observed in the Raman spectra, owing to the Bi-induced biaxial strain and the alloying effect as well.
7.	Yapparov, Rinat, et al. (author) Optimization of barrier height in InGaN quantum wells for rapid interwell carrier transport and low nonradiative recombination 2020 In: Applied Physics Expres. - : IOP Publishing. - 1882-0778 .- 1882-0786. ; 13:12 Journal article (peer-reviewed)abstract Rapid interwell carrier transport is a key process for a uniform carrier distribution and reduced Auger recombination in multiple quantum well (MQW) light emitting devices. In this work, the interwell transport has been studied by time-resolved photoluminescence in In0.12Ga0.88N MQWs with InxGa1-xN (x = 0 0.06) and Al0.065Ga0.935N barriers. Only for the InGaN barriers the transport is efficient. However, introduction of In into the barriers is accompanied by an increase of the nonradiative recombination at QW interfaces. Still, even with the increased Shockley-Read-Hall recombination, structures with InGaN barriers might be advantageous for high power devices because of the reduced Auger recombination.
8.	Yue, L., et al. (author) Novel InGaPBi single crystal grown by molecular beam epitaxy 2015 In: Applied Physics Express. - : IOP Publishing. - 1882-0786 .- 1882-0778. ; 8:4, s. Art. no. 041201- Journal article (peer-reviewed)abstract InGaPBi crystalline thin films with up to 2.1% bismuth concentration have been grown on GaAs substrates by molecular beam epitaxy. Rutherford backscattering spectrometry confirms that the majority of Bi atoms are located at substitutional lattice sites. The films exhibit good surface, structural, and interface quality, and their strains can be tuned from tensile to compressive by increasing the Bi content. InBi LO and GaBi LO vibrational modes in Raman spectroscopy were observed, and their intensities increased with Bi concentration. A weak photoluminescence signal was observed at 1.78 eV at room temperature for the sample with a Bi content of 0.5%.
9.	Fujii, Hitoshi, et al. (author) Interstitial Donor Codoping Method in (Ga, Mn)As to Increase Solubility of Mn and Curie Temperature 2011 In: APPL PHYS EXPRESS. - : The Japan Society of Applied Physics (JSAP). - 1882-0778. ; 4:4 Journal article (peer-reviewed)abstract Based on first principles calculations, we propose a solubility control method of magnetic impurities in dilute magnetic semiconductors (DMSs). The low solubility of Mn in (Ga, Mn)As is experimentally and theoretically known. We show that donor atoms, such as Li, introduced at the interstitial sites in GaAs enhance the solubility of Mn. As a result, Mn can be doped to more than 20% in GaAs in the thermal equilibrium condition. The same effect can be seen when we dope Mn in GaAs with other interstitial donors, such as H, Na, K, Be, Mg, Ca, Cu, and Ag.
10.	Hayton, James, et al. (author) Pi-Conjugated Molecular Nanowire Stacks Investigated by Frequency-Modulation Atomic Force Microscopy in the qPlus Configuration 2009 In: APPLIED PHYSICS EXPRESS. - 1882-0778. ; 2:9, s. 091501- Journal article (peer-reviewed)abstract Self-assembled pi-conjugated nanowire stacks were imaged using a tuning-fork probe mounted in the qPlus configuration in frequency modulation mode under ultrahigh vacuum. High resolution topographic and dissipation images demonstrate the applicability of such probes to soft conjugated materials, with sub-molecular resolution achieved perpendicular to the stacking axis. A new insight is gained from the damping contrast into the local mechanical properties of edge-on pi-conjugated stacks.
11.	Jayathilaka, Charith, et al. (author) Improved efficiency of electrodeposited p-CuO/n-Cu2O heterojunction solar cell 2015 In: Applied Physics Express. - 1882-0778. ; 8:6 Journal article (peer-reviewed)abstract We report electrodeposition of n-type cuprous oxide (Cu2O) films on p-type CuO films electrodeposited on Ti substrates for forming p-CuO/n-Cu2O heterostructures. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis revealed that the films had good structural quality, with substrates being well-covered by the films. The p-CuO/n-Cu2O heterojunctions exhibited good photovoltaic properties and diode characteristics. The surfaces of Cu2O films subject to ammonium sulfide treatment exhibited enhanced photocurrents. Under AM 1.5 illumniation, the obtained sulfur-treated and annealed Ti/p-CuO/n-Cu2O/Au solar cell structure yielded energy conversion efficiency of 0.64%, with V-oc = 220mV and J(sc) = 6.8 mAcm(-2).
12.	Le Febvrier, Arnaud, et al. (author) P-type Al-doped Cr-deficient CrN thin films for thermoelectrics 2018 In: APPLIED PHYSICS EXPRESS. - : IOP PUBLISHING LTD. - 1882-0778. ; 11:5 Journal article (peer-reviewed)abstract Thermoelectric properties of chromium nitride (CrN)-based films grown on c-plane sapphire by dc reactive magnetron sputtering were investigated. In this work, aluminum doping was introduced in CrN (degenerate n-type semiconductor) by co-deposition. Under the present deposition conditions, over-stoichiometry in nitrogen (CrN1+delta) rock-salt structure is obtained. A p-type conduction is observed with nitrogen-rich CrN combined with aluminum doping. The Cr0.96Al0.04N1.17 film exhibited a high Seebeck coefficient and a sufficient power factor at 300 degrees C. These results are a starting point for designing p-type/n-type thermoelectric materials based on chromium nitride films, which are cheap and routinely grown on the industrial scale. (C) 2018 The Japan Society of Applied Physics
13.	Li, Borui, et al. (author) Acoustic surface transformation realized by acoustic-null materials using bilayer natural materials 2017 In: APPLIED PHYSICS EXPRESS. - : IOP PUBLISHING LTD. - 1882-0778. ; 10:11 Journal article (peer-reviewed)abstract We propose a general method, known as acoustic surface transformation (AST), to design novel acoustic devices and study the realization of such devices by using naturally available materials in broadband acoustic frequencies. All devices designed by AST only need one anisotropic homogeneous acoustic-null material (ANM). We design the ANM by exploiting natural material-based metal-fluid structures and verify that by numerical simulation. Unlike traditional methods, no complicated mathematical calculations are needed. We only need to design the geometrical shapes of the input and output surfaces of the devices. The proposed method will pave a new road for future acoustic design.
14.	Li, Borui, et al. (author) Investigation of light trapping effect in hyperbolic metamaterial slow-light waveguides 2015 In: APPLIED PHYSICS EXPRESS. - 1882-0778. ; 8:8 Journal article (peer-reviewed)abstract A hyperbolic metamaterial waveguide can reduce the group velocity of light down to zero by tuning a waveguide structure. The light trapping capability of a tapered hyperbolic metamaterial waveguide is comprehensively studied in this work. Although a pulse of light cannot be trapped forever in such a waveguide, the duration that light remains trapped can be flexibly prolonged by adjusting the volume filling ratio of the metamaterial or the material dispersion, in order to achieve a sufficiently long trapping time for practical applications.
15.	Li, Borui, et al. (author) Reducing the dimensions of acoustic devices using anti-acoustic-null media 2018 In: APPLIED PHYSICS EXPRESS. - : IOP PUBLISHING LTD. - 1882-0778. ; 11:2 Journal article (peer-reviewed)abstract An anti-acoustic-null medium (anti-ANM), a special homogeneous medium with anisotropic mass density, is designed by transformation acoustics (TA). Anti-ANM can greatly compress acoustic space along the direction of its main axis, where the size compression ratio is extremely large. This special feature can be utilized to reduce the geometric dimensions of classic acoustic devices. For example, the height of a parabolic acoustic reflector can be greatly reduced. We also design a brass-air structure on the basis of the effective medium theory to materialize the anti-ANM in a broadband frequency range. Numerical simulations verify the performance of the proposed anti-ANM.
16.	Moubah, Reda, et al. (author) Anisotropic Magnetostriction and Domain Wall Motion in Sm10Co90 Amorphous Films 2013 In: APPL PHYS EXPRESS. - 1882-0778. ; 6:5, s. 053004- Journal article (peer-reviewed)abstract We show that Sm10Co90 amorphous films exhibit anisotropic magnetostriction effects when a magnetic field is applied perpendicular to the imprinted easy axis of magnetization. At low applied fields (0-100 mT), we observe strong anisotropy in the field response. Parallel to the applied field, the strain scales linearly with the applied field while the strain perpendicular to the field direction ( easy axis) is close to the detection limit. This behavior is accompanied by zigzag domain wall motion with the corners pointing along the easy axis. The origin of the anisotropic magnetostriction is discussed.
17.	Moubah, Reda, et al. (author) Soft Room-Temperature Ferromagnetism of Carbon-Implanted Amorphous Fe93Zr7 Films 2013 In: APPL PHYS EXPRESS. - : Japan Society of Applied Physics. - 1882-0778. ; 6:5, s. 053001- Journal article (peer-reviewed)abstract We report on the effect of carbon implantation on the structural, electronic, and magnetic properties of Fe93Zr7 (FeZr) amorphous films. Extended X-ray absorption fine structure measurements on (FeZr)(100-x)C-x (x = 0, 5.5, and 11) indicate the incorporation of carbon in the FeZr matrix, with an increase of the Fe-Fe distance by implanting carbon. X-ray photoelectron spectroscopy measurements reveal the creation of Fe-C bonds after implantation. A significant enhancement of the Curie temperature and decrease of the coercivity are observed in the carbon-implanted films. Moreover, the non collinear ferromagnetism of the as-grown FeZr film diminishes upon carbon implantation.
18.	Murakami, Hisashi, et al. (author) Homoepitaxial growth of beta-Ga2O3 layers by halide vapor phase epitaxy 2015 In: Applied Physics Express. - : Japan Society of Applied Physics. - 1882-0778. ; 8:1, s. 015503- Journal article (peer-reviewed)abstract Thick high-purity beta-Ga2O3 layers of high crystalline quality were grown homoepitaxially by halide vapor phase epitaxy (HVPE) using gaseous GaCl and O-2 on (001) beta-Ga2O3 substrates prepared by edge-defined film-fed growth. The surface morphology and structural quality of the grown layer improved with increasing growth temperature. X-ray diffraction omega-rocking curves for the (002) and (400) reflections for the layer grown at 1000 degrees C had small full widths at half maximum. Secondary ion mass spectrometry and electrical characteristics revealed that the growth of high-purity beta-Ga2O3 layers with low effective donor concentration (N-d - N-a less than 10(13) cm(-3)) is possible by HVPE. (C) 2015 The Japan Society of Applied Physics
19.	Ndebeka-Bandou, Camille, et al. (author) Dopant Engineering of Inter-Subband Linewidth and Lineshape in Multiwell Heterostructures 2013 In: Applied Physics Express. - 1882-0778. ; 6:9 Journal article (peer-reviewed)abstract We show by numerical diagonalization of the electronic Hamiltonian including screened coulombic impurities that the inter-subband absorption lineshape and linewidth in heterostructures can be controlled by a suitable location of the dopants. We also point out that the usual optical conductivity calculations that employ the self-consistent Born approximation often lead to incorrect lineshapes, although the trends for the linewidths versus the dopant location are the same as found in the present numerical approach. (c) 2013 The Japan Society of Applied Physics
20.	Nipoti, Roberta, et al. (author) Microwave Annealing of Very High Dose Aluminum-Implanted 4H-SiC 2011 In: APPL PHYS EXPRESS. - 1882-0778. ; 4:11, s. 111301- Journal article (peer-reviewed)abstract A microwave heating technique has been used for the electrical activation of Al(+) ions implanted in semi-insulating 4H-SiC. Annealing temperatures in the range of 2000-2100 degrees C and annealing time of 30 s have been used. The implanted Al concentration has been varied from 5 x 10(19) to 8 x 10(20) cm(-3). A minimum resistivity of 2 x 10(-2) Omega cm and about 70% electrical activation of the implanted Al have been measured at room temperature for an implanted Al concentration of 8 x 10(20) cm(-3) and microwave annealing at 2100 degrees C for 30 s.
21.	ul Hassan Alvi, Naveed, et al. (author) Highly Sensitive and Fast Anion-Selective InN Quantum Dot Electrochemical Sensors 2013 In: APPLIED PHYSICS EXPRESS. - : Japan Society of Applied Physics. - 1882-0778. ; 6:11 Journal article (peer-reviewed)abstract Epitaxial InN quantum dots (QDs) are demonstrated as ion-selective electrode for potentiometric anion concentration measurements. The sensor reveals high sensitivity above 90 mV/decade for the detection of chlorine and hydroxyl ions in sodium chloride (NaCl), calcium chloride (CaCl2), and sodium hydroxide (NaOH) solutions. The response time is less than two seconds after which the signal is very stable and repeatable. The sensitivity for the InN QDs is about two times that for a reference InN thin film and the response time is about five times shorter. In pH buffer solutions the sensor reveals no clear response to cations. A model is presented for the high sensitivity, fast response, and ion selectivity based on the unique electronic properties of the InN surface together with the zero-dimensional nature of the QDs.
22.	UŽdavinys, Tomas Kristijonas, et al. (author) Impact of surface morphology on the properties of light emission in InGaN epilayers 2018 In: Applied Physics Express. - : Japan Society of Applied Physics. - 1882-0778. ; 11:5 Journal article (peer-reviewed)abstract Scanning near-field optical microscopy was used to study the influence of the surface morphology on the properties of light emission and alloy composition in InGaN epitaxial layers grown on GaN substrates. A strong correlation between the maps of the photoluminescence (PL) peak energy and the gradient of the surface morphology was observed. This correlation demonstrates that the In incorporation strongly depends on the geometry of the monolayer step edges that form during growth in the step-flow mode. The spatial distribution of nonradiative recombination centers-evaluated from PL intensity maps-was found to strongly anticorrelate with the local content of In atoms in the InGaN alloy.
23.	van Breemen, Albert J. J. M., et al. (author) Crossbar arrays of nonvolatile, rewritable polymer ferroelectric diode memories on plastic substrates 2014 In: APPLIED PHYSICS EXPRESS. - : Japan Society of Applied Physics. - 1882-0778. ; 7:3 Journal article (peer-reviewed)abstract In this paper, we demonstrate a scalable and low-cost memory technology using a phase separated blend of a ferroelectric polymer and a semiconducting polymer as data storage medium on thin, flexible polyester foils of only 25 mu m thickness. By sandwiching this polymer blend film between rows and columns of metal electrode lines where each intersection makes up one memory cell, we obtained 1 kbit cross bar arrays with bit densities of up to 10 kbit/cm(2). (C) 2014 The Japan Society of Applied Physics

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