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19 Feb 2001

Volume 78, Issue 8, pp. 1023-1163

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Structural and magnetoresistance properties of La2/3Ca1/3MnO3 thin films on buffered silicon substrates

D. Kumar, S. Chattopadhyay, Walter M. Gilmore, C. B. Lee, J. Sankar, A. Kvit, A. K. Sharma, J. Narayan, S. V. Pietambaram, and Rajiv K. Singh

Appl. Phys. Lett. 78, 1098 (2001); http://dx.doi.org/10.1063/1.1350603 (3 pages) | Cited 6 times

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We report an epitaxial growth of LCMO (La2/3Ca1/3MnO3) film on Si by using a highly conducting diffusion barrier layer of TiN. In order to achieve epitaxial growth of LCMO films, MgO, and SrTiO3 films were used as intermediate layers between LCMO and TiN layers. The results have indicated that the properties of LCMO films on Si substrates, deposited under an optimized condition, are on par with the properties of LCMO films on conventional oxide substrates such as LaAlO3 and SrTiO3 in terms of paramagnetic to ferromagnetic transition temperature, insulator to metal transition temperature, and magnetoresistance ratio. © 2001 American Institute of Physics.
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75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
68.65.Ac Multilayers
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.50.Dd Nonmetallic ferromagnetic materials
72.60.+g Mixed conductivity and conductivity transitions
81.15.Fg Pulsed laser ablation deposition

Electron spin manipulation using semimagnetic resonant tunneling diodes

Th. Gruber, M. Keim, R. Fiederling, G. Reuscher, W. Ossau, G. Schmidt, L. W. Molenkamp, and A. Waag

Appl. Phys. Lett. 78, 1101 (2001); http://dx.doi.org/10.1063/1.1350600 (3 pages) | Cited 50 times

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One major challenge for the development of spintronic devices is the control of the spin polarization of an electron current. We propose and demonstrate the use of a BeTe/Zn1−xSe/BeTe double barrier resonant tunneling diode for the injection of a spin-polarized electron current into GaAs and the manipulation of the spin orientation of the injected carriers via an external voltage. A spin polarization of up to 80% can be observed with a semimagnetic layer of only 3.5 nm thickness. By changing the resonance condition via the external voltage, the degree of spin polarization can be varied, though a complete spin switching has not yet been accomplished. © 2001 American Institute of Physics.
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85.75.Mm Spin polarized resonant tunnel junctions
75.50.Pp Magnetic semiconductors
85.30.Kk Junction diodes
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)

Low-temperature ordering of L10–CoPt thin films promoted by Sn, Pb, Sb, and Bi additives

O. Kitakami, Y. Shimada, K. Oikawa, H. Daimon, and K. Fukamichi

Appl. Phys. Lett. 78, 1104 (2001); http://dx.doi.org/10.1063/1.1346628 (3 pages) | Cited 77 times

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We have studied the effect of additional elements of Sn, Pb, Sb, and Bi on the ordering of L10–CoPt films. All of these additives are demonstrated to be very effective to promote the ordering and developing of a very large coercivity of the samples annealed at 400 °C. It is worth noting that this annealing temperature for ordering is 200 °C lower than that of pure CoPt. The crystallographic and chemical analyses have revealed that these additives easily diffuse and segregate onto the film surfaces by postannealing because of their very low surface free energy and extremely low solubility in Co. Therefore, it seems reasonable to conclude that the ordering in the CoPt film is significantly promoted at much lower temperature by the aid of a lot of defects produced by the additives excreted by postannealing. © 2001 American Institute of Physics.
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68.55.-a Thin film structure and morphology
75.50.Ss Magnetic recording materials
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.70.Ak Magnetic properties of monolayers and thin films
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
64.75.-g Phase equilibria
68.35.Md Surface thermodynamics, surface energies

Band-gap states and ferroelectric restoration in strontium bismuth tantalate

Biao Li, F. Koch, and L. Chu

Appl. Phys. Lett. 78, 1107 (2001); http://dx.doi.org/10.1063/1.1347011 (3 pages) | Cited 4 times

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By means of photoluminescence (PL) and sub-band-gap (sub-Eg) optical illumination, the degradation and restoration of ferroelectric properties in strontium bismuth tantalate thin films have been investigated, and the existence of band-gap states is demonstrated. It is shown that the suppression and recovery of ferroelectricity are closely correlated with the change of PL intensity, since both switchable polarization and PL are related to Ta5+ ions in the TaO6 octahedron. Furthermore, the electric-field-induced restoration increases dramatically by the aid of sub-band-gap light (2.5 eV ⩽ hν ⩽ Eg) illumination absorbed in band-gap states. © 2001 American Institute of Physics.
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77.55.-g Dielectric thin films
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
71.20.Ps Other inorganic compounds
77.80.Fm Switching phenomena
77.22.Ej Polarization and depolarization
78.66.Nk Insulators
78.55.Hx Other solid inorganic materials

Low-field magnetoresistance in nanosized La0.7Sr0.3MnO3/Pr0.5Sr0.5MnO3 composites

J.-M. Liu, G. L. Yuan, H. Sang, Z. C. Wu, X. Y. Chen, Z. G. Liu, Y. W. Du, Q. Huang, and C. K. Ong

Appl. Phys. Lett. 78, 1110 (2001); http://dx.doi.org/10.1063/1.1350602 (3 pages) | Cited 42 times

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Nanosized La0.7Sr0.3MnO3/Pr0.5Sr0.5MnO3 (LSMO1−xPSMOx) ceramic composites are prepared using solid-sate sintering. Their microstructural, electro- and magnetotransport properties are characterized by means of various techniques. It is found that the antiferromagnetic/ferromagnetic coupling between PSMO/LSMO at low temperature and the weak ferromagnetic order of PSMO at high temperature results in enhanced low-field magnetoresistance (LFMR) of the composites. With increasing temperature up to 250 K the observed LFMR decays more slowly than that for pure LSMO and this behavior may be explained by the spin coupling near boundaries between LSMO and PSMO grains. © 2001 American Institute of Physics.
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75.50.Tt Fine-particle systems; nanocrystalline materials
75.47.Gk Colossal magnetoresistance
75.50.Ee Antiferromagnetics
75.50.Cc Other ferromagnetic metals and alloys
75.30.Et Exchange and superexchange interactions

Evolution of barrier asymmetry in magnetic tunnel junctions

H. Brückl, J. Schmalhorst, G. Reiss, G. Gieres, and J. Wecker

Appl. Phys. Lett. 78, 1113 (2001); http://dx.doi.org/10.1063/1.1350601 (3 pages) | Cited 10 times

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Magnetic tunnel junctions usually consist of different layer stacks at the two sides of the tunneling barrier. The exposure of these junctions to high temperatures thus can induce large asymmetries in the electronic potential with respect to the barrier. Using the example of Co/Cu/Co/Al2O3/Co tunnel junctions, we show that the measured current/voltage characteristics develop a large asymmetry upon annealing at a temperature larger than 230 °C. This is accompanied by a Cu enrichment at one side of the barrier and cannot be explained by simply using the work function differences between the electrode materials. Thus, a Cu–Al2O3 intermixing zone at the barrier interface must be taken into account, which leads to an asymmetric step-like barrier shape. The interpretation is supported by numerical evaluation of model barriers which reproduce the experimental asymmetries if an intermixing zone of only 0.2 nm thickness is assumed. © 2001 American Institute of Physics.
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75.45.+j Macroscopic quantum phenomena in magnetic systems
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
73.30.+y Surface double layers, Schottky barriers, and work functions
66.30.Ny Chemical interdiffusion; diffusion barriers
68.35.Fx Diffusion; interface formation
85.75.Dd Magnetic memory using magnetic tunnel junctions
75.50.Ee Antiferromagnetics
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Temperature dependence of polarization and charge dynamics on the BaTiO3(100) surface by scanning probe microscopy

Sergei V. Kalinin and Dawn A. Bonnell

Appl. Phys. Lett. 78, 1116 (2001); http://dx.doi.org/10.1063/1.1348303 (3 pages) | Cited 36 times

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Variable-temperature atomic force microscopy, piezoresponse force microscopy (PFM), and scanning surface potential microscopy were combined to determine the temperature response of polarization and screening charge on BaTiO3(100) surfaces. The ferroelectric-domain induced surface corrugations and piezoelectric response decrease with temperature and disappear at the Curie temperature. The temperature dependence of the PFM contrast is explained within the framework of the Ginzburg–Devonshire theory with the effect of a dielectric tip-surface gap taken into account. The temperature dependence of the surface potential contrast is ascribed to the interplay between the release of the screening charges with temperature and their slow relaxation. The results indicate that surface potential polarity is reversed relative to that expected from polarization orientation on BaTiO3 in ambient. © 2001 American Institute of Physics.
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77.65.-j Piezoelectricity and electromechanical effects
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
68.37.Ps Atomic force microscopy (AFM)
77.22.Ej Polarization and depolarization
77.80.B- Phase transitions and Curie point
77.80.Dj Domain structure; hysteresis
77.22.Gm Dielectric loss and relaxation

Ferroelectric properties of alkoxy-derived CaBi4Ti4O15 thin films on Pt-passivated Si

Kazumi Kato, Kazuyuki Suzuki, Kaori Nishizawa, and Takeshi Miki

Appl. Phys. Lett. 78, 1119 (2001); http://dx.doi.org/10.1063/1.1349871 (3 pages) | Cited 40 times

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CaBi4Ti4O15 (CBTi144) thin films were prepared by spin coating a precursor solution of metal alkoxides. As-deposited thin films began crystallization below 550 °C and reached full crystallinity of a single phase of layered perovskite at 650 °C via rapid thermal annealing in oxygen. The 650 °C annealed CBTi144 thin film showed random orientation on Pt-passivated Si substrate and exhibited P-E hysteresis loops. The remanent polarization (Pr) and coercive electric field (Ec) were 9.4 μC/cm2 and 106 kV/cm, respectively, at 11 V. The dielectric constant and loss factor were 300 and 0.033, respectively, at 100 kHz. © 2001 American Institute of Physics.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.80.Dj Domain structure; hysteresis
77.55.-g Dielectric thin films
77.22.Ch Permittivity (dielectric function)
77.22.Ej Polarization and depolarization
77.22.Gm Dielectric loss and relaxation

Thickness dependence of ferroelectric polarization switching in poly(vinylidene fluoride–trifluoroethylene) spin cast films

Feng Xia, Haisheng Xu, Fei Fang, B. Razavi, Z.-Y. Cheng, Yu Lu, Baomin Xu, and Q. M. Zhang

Appl. Phys. Lett. 78, 1122 (2001); http://dx.doi.org/10.1063/1.1351848 (3 pages) | Cited 46 times

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In poly(vinylidene fluoride–trifluoroethylene) copolymer spin cast films, it has been observed that the polarization switching time increases as the film thickness is reduced to below 1 μm. We will show that this change with film thickness can be divided into two thickness regimes, i.e., those above 120–150 nm and those below that thickness. For films thicker than 120–150 nm, the change in the switching behavior is due to interface effects that can be modeled by an effective interface layer with lower dielectric constant that is in series with the film. For films below 120–150 nm thickness, there is an additional and very large increase of the switching time with reduced film thickness. This additional effect is caused by the precipitous drop of the crystallinity in films at this thickness range. © 2001 American Institute of Physics.
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77.84.Jd Polymers; organic compounds
77.55.-g Dielectric thin films
77.80.Fm Switching phenomena
77.22.Ej Polarization and depolarization
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Preparation and photoluminescence of highly ordered TiO2 nanowire arrays

Y. Lei, L. D. Zhang, G. W. Meng, G. H. Li, X. Y. Zhang, C. H. Liang, W. Chen, and S. X. Wang

Appl. Phys. Lett. 78, 1125 (2001); http://dx.doi.org/10.1063/1.1350959 (3 pages) | Cited 172 times

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Highly ordered TiO2 nanowire (TN) arrays were prepared in anodic alumina membranes (AAMs) by a sol-gel method. The TNs are single crystalline anatase phase with uniform diameters around 60 nm. At room temperature, photoluminescence (PL) measurements of the TN arrays show a visible broadband with three peaks, which are located at about 425, 465, and 525 nm that are attributed to self-trapped excitons, F, and F+ centers, respectively. A model is also presented to explain the PL intensity drop-down of the TN arrays embedded in AAMs: the blue PL band of AAMs arises from the F+ centers on the pore walls, and the TNs first form in the center area of the pores and then extend to the pore walls. © 2001 American Institute of Physics.
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81.15.Lm Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids)
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
81.07.Bc Nanocrystalline materials
78.55.Mb Porous materials
61.46.-w Structure of nanoscale materials
71.35.Aa Frenkel excitons and self-trapped excitons

Large-scale production of nanocrystals by laser ablation of microparticles in a flowing aerosol

W. T. Nichols, J. W. Keto, D. E. Henneke, J. R. Brock, G. Malyavanatham, M. F. Becker, and H. D. Glicksman

Appl. Phys. Lett. 78, 1128 (2001); http://dx.doi.org/10.1063/1.1347385 (3 pages) | Cited 26 times

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We experimentally demonstrate the production of nanoparticles by laser ablation of microparticles entrained at high density in a flowing aerosol. The currently measured production rate of 20 grams per hour could be scaled to industrially useful rates. We have characterized the size distribution of particles and found nearly monodisperse distributions where mean sizes were smaller and varied less with laser fluence than was observed for ablation of microparticles held on flat plates. Mean size was controlled from 4–20 nm by varying the type and pressure of carrier gas. We found Ag and CdSe nanoparticles were crystalline having few dislocations. Materials tested included metals (Ag, Au, and W), semiconductors (Si, CdSe, GaN, and ZnO), ceramics (WC, SiC, and YBa2Cu3O7), and a ferroelectric. Two types of collection processes are described that preserve the nonagglomerated nature of the particles, even at high mass densities. © 2001 American Institute of Physics.
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52.38.Mf Laser ablation
79.20.Ds Laser-beam impact phenomena
81.20.Rg Aerosols in materials synthesis and processing
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
81.07.Bc Nanocrystalline materials

Stimulated blue emission in reconstituted films of ultrasmall silicon nanoparticles

M. H. Nayfeh, N. Barry, J. Therrien, O. Akcakir, E. Gratton, and G. Belomoin

Appl. Phys. Lett. 78, 1131 (2001); http://dx.doi.org/10.1063/1.1347398 (3 pages) | Cited 78 times

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We dispersed electrochemical etched Si into a colloid of ultrabright blue luminescent nanoparticles (1 nm in diameter) and reconstituted it into films or microcrystallites. When the film is excited by a near-infrared two-photon process at 780 nm, the emission exhibits a sharp threshold near 106 W/cm2, rising by many orders of magnitude, beyond which a low power dependence sets in. Under some conditions, spontaneous recrystallization forms crystals of smooth shape from which we observe collimated beam emission, pointing to very large gain coefficients. The results are discussed in terms of population inversion, produced by quantum tunneling or/and thermal activation, and stimulated emission in the quantum confinement-engineered Si–Si phase found only on ultrasmall Si nanoparticles. The Si–Si phase model provides gain coefficients as large as 103–105 cm−1. © 2001 American Institute of Physics.
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78.66.Db Elemental semiconductors and insulators
78.45.+h Stimulated emission
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.55.Ap Elemental semiconductors
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Characterization of RuO2 electrodes on Zr silicate and ZrO2 dielectrics

Huicai Zhong, Greg Heuss, Veena Misra, Hongfa Luan, Choong-Ho Lee, and Dim-Lee Kwong

Appl. Phys. Lett. 78, 1134 (2001); http://dx.doi.org/10.1063/1.1347402 (3 pages) | Cited 33 times

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The rutile stoichiometric phase of RuO2, deposited via reactive sputtering, was evaluated as a gate electrode on chemical vapor deposited ZrO2 and Zr silicate for Si–p-type metal–oxide–semiconductor (PMOS) devices. Thermal and chemical stability of the electrodes was studied at annealing temperatures of 400, 600, and 800 °C in N2. X-ray diffraction was measured to study grain structure and interface reactions. The resistivity of RuO2 films was 65.0 μΩ cm after 800 °C annealing. Electrical properties were evaluated on MOS capacitors, which indicated that the work function of RuO2 was ∼ 5.1 eV, compatible with PMOS devices. Post-RuO2 gate annealing up to 800 °C, resulted in only a 1.4 Å equivalent oxide thickness (Tox-eq) change and 0.2 V flatband voltage change for Zr silicate and a 4 Å Tox-eq change for ZrO2 dielectrics. Tantalum electrodes were also studied on ZrO2 as a comparison of the stability of RuO2 electrodes. © 2001 American Institute of Physics.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
81.15.Cd Deposition by sputtering
77.84.-s Dielectric, piezoelectric, ferroelectric, and antiferroelectric materials
68.60.Dv Thermal stability; thermal effects
84.32.Tt Capacitors
73.30.+y Surface double layers, Schottky barriers, and work functions

Josephson-junction arrays as high-efficiency sources of coherent millimeter-wave radiation

B. Vasilić, S. V. Shitov, C. J. Lobb, and P. Barbara

Appl. Phys. Lett. 78, 1137 (2001); http://dx.doi.org/10.1063/1.1350431 (3 pages) | Cited 11 times

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Recent experiments have indicated that Josephson-junction arrays can radiate coherently in a laser-like fashion, as predicted by theoretical work in the 1970s. We present results from measurements of high-efficiency Josephson-junction arrays coupled to resonant cavities. In one of our samples with four columns and 36 rows, the dc to ac (180 GHz) conversion efficiency reaches an asymptotic value of about 32%. Using a simple circuit model we show that we have achieved optimal dc to ac conversion in this sample. © 2001 American Institute of Physics.
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85.25.Cp Josephson devices
84.40.-x Radiowave and microwave (including millimeter wave) technology

Single-electron inverter

C. P. Heij, P. Hadley, and J. E. Mooij

Appl. Phys. Lett. 78, 1140 (2001); http://dx.doi.org/10.1063/1.1345822 (3 pages) | Cited 17 times

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A single-electron inverter was fabricated that switches from a high output to a low output when a fraction of an electron is added to the input. For the proper operation of the inverter, the two single-electron transistors that make up the inverter must exhibit voltage gain. Voltage gain was achieved by fabricating a combination of parallel-plate gate capacitors and small tunnel junctions in a two-layer circuit. Voltage gain of 2.6 was attained at 25 mK and remained larger than one for temperatures up to 140 mK. The temperature dependence of the gain agrees with the orthodox theory of single-electron tunneling. © 2001 American Institute of Physics.
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85.35.Gv Single electron devices
84.30.Jc Power electronics; power supply circuits
84.30.Qi Modulators and demodulators; discriminators, comparators, mixers, limiters, and compressors
85.35.Ds Quantum interference devices
84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
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Atomic force microscopy detects transient frictional contrasts in apoptotic cells induced by deprivation of interleukin-3

M. Girasole, A. Cricenti, R. Generosi, I. Silvestri, P. Gazzaniga, D. Pozzi, and A. M. Aglianò

Appl. Phys. Lett. 78, 1143 (2001); http://dx.doi.org/10.1063/1.1350976 (3 pages) | Cited 2 times

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The morphological changes of murine hematopoietic 32D Cl3-A cell line, in which apoptosis was induced by deprivation of interleukin-3 (IL-3) from the culture medium, were studied through air operating atomic force microscopy. The subtraction of IL-3 determines the appearing of blebs on plasma membrane and cell fragmentation in several residual bodies. Areas of strong contrast in the friction images, which are nearly absent in control and necrotic cells, were detected with percentage that peaks at 6 h of IL-3 deprivation. These are the results revealing that transient modification of the plasma membrane accompanies the first steps of apoptosis pathway. © 2001 American Institute of Physics.
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87.64.Dz Scanning tunneling and atomic force microscopy
87.17.-d Cell processes
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Properties of surface waves determined via bistatic terahertz impulse ranging

M. T. Reiten, D. Grischkowsky, and R. A. Cheville

Appl. Phys. Lett. 78, 1146 (2001); http://dx.doi.org/10.1063/1.1350418 (3 pages) | Cited 9 times

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A bistatic terahertz impulse ranging system has permitted the full isolation and direct measurements of the surface wave loss and dispersion for terahertz frequencies on a dielectric cylinder. This system permits ranging investigations with variable bistatic angles between the source and detector. Direct, frequency dependent comparisons of surface wave loss and propagation velocity are compared to Mie theory and previous measurements of surface wave propagation over a 1 THz bandwidth. The observed radiation from the surface waves is seen to depend on the path of the radiation in and along the scatterer. © 2001 American Institute of Physics.
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41.20.Jb Electromagnetic wave propagation; radiowave propagation
43.35.Pt Surface waves in solids and liquids
77.65.Dq Acoustoelectric effects and surface acoustic waves (SAW) in piezoelectrics
68.35.Iv Acoustical properties

Electrospinning: A whipping fluid jet generates submicron polymer fibers

Y. M. Shin, M. M. Hohman, M. P. Brenner, and G. C. Rutledge

Appl. Phys. Lett. 78, 1149 (2001); http://dx.doi.org/10.1063/1.1345798 (3 pages) | Cited 215 times

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Polymeric fibers with diameters in the range from 50 nm to 5 μm are produced by accelerating a fluid jet in an electric field, in a process known as “electrospinning.” Here we show that an essential element of the process is a fluid instability, the rapidly whipping jet. The phenomena responsible for the onset of whipping are revealed by a linear instability analysis that describes the jet behavior in terms of known fluid properties and operating conditions. The behavior of two competing instabilities, the Rayleigh mode and the axisymmetric conducting mode, is also described. The results are summarized using operating diagrams, delineating regimes of operation in electrospinning, which are in good agreement with experimental observations. © 2001 American Institute of Physics.
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81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
47.15.Fe Stability of laminar flows
47.27.wg Turbulent jets

Metal foam evolution studied by synchrotron radioscopy

John Banhart, Heiko Stanzick, Lukas Helfen, and Tilo Baumbach

Appl. Phys. Lett. 78, 1152 (2001); http://dx.doi.org/10.1063/1.1350422 (3 pages) | Cited 32 times

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High-intensity synchrotron x-ray radioscopy was used to obtain real-time images of foaming metals, thus allowing the formation, growth, and decay of such systems to be studied. Bubble generation, foam coalescence and drainage of an aluminum-based alloy foam were investigated. Although the foaming process appears to be very similar to the formation of aqueous foams, the observed rupture behavior of thin metal films suggests that the processes responsible for metal foam stabilization and destabilization must be quite different. © 2001 American Institute of Physics.
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82.70.Rr Aerosols and foams

Ultrafast two-dimensional ultrasonic speckle velocimetry: A tool in flow imaging

Laurent Sandrin, Sébastien Manneville, and Mathias Fink

Appl. Phys. Lett. 78, 1155 (2001); http://dx.doi.org/10.1063/1.1350622 (3 pages) | Cited 12 times

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A technique for imaging fluid flows is proposed, based on the ultrafast analysis of the ultrasonic speckle signal backscattered by particles following the flow. Such an “ultrasonic speckle velocimetry” (USV) provides two-dimensional measurements of one component of the fluid velocity field at about 5000 frames per second. USV is applied to three different flows and future improvements of the technique are described. © 2001 American Institute of Physics.
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47.80.-v Instrumentation and measurement methods in fluid dynamics
43.35.Yb Ultrasonic instrumentation and measurement techniques
06.30.Gv Velocity, acceleration, and rotation

Observation of multiple nearly monoenergetic electron production by heated pyroelectric crystals in ambient gas

J. D. Brownridge, S. M. Shafroth, D. W. Trott, B. R. Stoner, and W. M. Hooke

Appl. Phys. Lett. 78, 1158 (2001); http://dx.doi.org/10.1063/1.1342209 (2 pages) | Cited 15 times

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Multiple production of nearly monoenergetic electrons at a given pyroelectric crystal surface charge density is observed on cooling or heating the crystal in ambient gas. Typically, the +z base of a 5 mm diam×5 mm crystal of LiNbO3 is heated to 100 °C and then let cool to 23 °C in dry N2 at 10−2–10−6 Torr. The electron spectrum consists of a series of peaks equally spaced in energy and having decreasing intensity with order superimposed on a continuously decreasing background. The higher-order peaks and the high-energy continuum are due to two or more electrons hitting the surface barrier detector within its resolving time (∼1 μs). © 2001 American Institute of Physics.
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79.75.+g Exoelectron emission
77.70.+a Pyroelectric and electrocaloric effects
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
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Comment on “Optical and acoustic phonon modes in self-organized Ge quantum dot superlattices” [Appl. Phys. Lett. 76, 586 (2000)]

Peter Y. Yu

Appl. Phys. Lett. 78, 1160 (2001); http://dx.doi.org/10.1063/1.1350589 (2 pages) | Cited 3 times

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Abstract Unavailable
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63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
78.66.Db Elemental semiconductors and insulators
81.05.Cy Elemental semiconductors
78.67.Hc Quantum dots
68.65.Cd Superlattices
68.35.Ja Surface and interface dynamics and vibrations
78.30.Am Elemental semiconductors and insulators
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Response to “Comment on ‘Optical and acoustic phonon modes in self-organized Ge quantum dot superlattices’ ” [Appl. Phys. Lett. 78, 1160 (2001)]

J. L. Liu, G. Jin, Y. S. Tang, Y. H. Luo, K. L. Wang, and D. P. Yu

Appl. Phys. Lett. 78, 1162 (2001); http://dx.doi.org/10.1063/1.1350590 (2 pages) | Cited 2 times

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Abstract Unavailable
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63.22.-m Phonons or vibrational states in low-dimensional structures and nanoscale materials
81.05.Cy Elemental semiconductors
81.07.Ta Quantum dots
68.35.Ja Surface and interface dynamics and vibrations
66.30.Ny Chemical interdiffusion; diffusion barriers
68.35.Fx Diffusion; interface formation
68.65.Hb Quantum dots (patterned in quantum wells)
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