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12 Apr 1993

Volume 62, Issue 15, pp. 1709-1847

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X‐ray diffraction investigation of single step and step‐graded SiGe alloy buffers for the growth of short‐period SimGen superlattices using reciprocal space mapping

E. Koppensteiner, P. Hamberger, G. Bauer, A. Pesek, H. Kibbel, H. Presting, and E. Kasper

Appl. Phys. Lett. 62, 1783 (1993); http://dx.doi.org/10.1063/1.109548 (3 pages) | Cited 13 times

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Double crystal and triple axis x‐ray diffractometry was used to characterize the structural properties of short period Si6Ge4 superlattices grown by molecular beam epitaxy on either a thin (20 nm) single step Si0.6Ge0.4 alloy buffer or on a thick step‐graded Si1−xGex(0<x<0.4, 700 nm thick) buffer followed by a 550 nm Si0.6Ge0.4 layer. Reciprocal space maps around the (004) and (224) reciprocal lattice points yield direct information on the strain status of the buffer and superlattice layers. For the thick step‐graded buffer indeed all layers with different Ge content are fully relaxed and thus the growth of an almost freestanding superlattice is possible.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
68.55.-a Thin film structure and morphology
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Metal semiconductor field effect transistor based on single crystal GaN

M. Asif Khan, J. N. Kuznia, A. R. Bhattarai, and D. T. Olson

Appl. Phys. Lett. 62, 1786 (1993); http://dx.doi.org/10.1063/1.109549 (2 pages) | Cited 184 times

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In this letter we report the fabrication and characterization of a metal semiconductor field effect transistor (MESFET) based on single crystal GaN. The GaN layer was deposited over sapphire substrate using low pressure metalorganic chemical vapor deposition. MESFET devices were fabricated on isolated mesas using TiAu for the source and drain ohmic contacts and silver for the gate Schottky. For devices with a gate length of 4 μm (channel opening, i.e., source to drain separation of 10 μm), a transconductance of 23 mS/mm was obtained at −1 V gate bias. Complete pinch‐off was observed for a gate potential of −12 V.
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85.30.Tv Field effect devices
85.30.De Semiconductor-device characterization, design, and modeling

Structural and electrical properties of BaTiO3 thin films grown on p‐InSb substrate by metalorganic chemical vapor deposition at low temperature

T. W. Kim, M. Jung, H. J. Kim, Y. S. Yoon, W. N. Kang, and S. S. Yom

Appl. Phys. Lett. 62, 1788 (1993); http://dx.doi.org/10.1063/1.109550 (3 pages) | Cited 7 times

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Metalorganic chemical vapor deposition of BaTiO3 on p‐InSb (111) using Ba(tmhd)2, Ti(OC3H7)4, and N2O via pyrolysis at low (∼300 °C) temperature was performed to produce high‐quality BaTiO3/p‐InSb (111) interfaces and BaTiO3 insulator gates with dielectric constants of high magnitude. Raman spectroscopy showed the optical phonon modes of a BaTiO3 thin film. The stoichiometry of the BaTiO3 film was investigated by Auger electron spectroscopy. Transmission electron microscopy showed that the BaTiO3 films had local epitaxial formations. Room‐temperature capacitance‐voltage measurements clearly revealed metal‐insulator‐semiconductor behavior for the samples with the BaTiO3 insulator gates, and the interface state densities at the BaTiO3/p‐InSb interfaces were approximately high 1011 eV−1 cm−2 at the middle of the InSb energy gap. The dielectric constant determined from the capacitance‐voltage measurements was as large as 743. These results indicate that the BaTiO3 layers grown at low temperature can be used for both high‐density dynamic‐memory and high‐speed applications.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.-a Thin film structure and morphology
77.55.-g Dielectric thin films

Dependence of steady‐state defect density in hydrogenated amorphous silicon on carrier generation rate studied over a wide range

Nobuhiro Hata, Gautam Ganguly, and Akihisa Matsuda

Appl. Phys. Lett. 62, 1791 (1993); http://dx.doi.org/10.1063/1.109551 (3 pages) | Cited 11 times

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Measurements of the steady‐state defect density (Nst) in hydrogenated amorphous silicon under illumination of pulse‐laser light, as well as of continuous light, were carried out; and the dependence of Nst on the effective rate of carrier generation (G) is presented. The values of G ranged from 8×1021 to 2.4×1023 cm−3 s−1, while the illumination temperature was kept at 30 or 105 °C. The results showed trends of Nst increasing with G similarly to the trends in the literature, but covered a higher and wider G range, and fitted a defect model which assumes a limited number of possible defect states.
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71.55.Jv Disordered structures; amorphous and glassy solids
61.72.Cc Kinetics of defect formation and annealing
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
72.80.Ng Disordered solids

Polythiophene field‐effect transistor with polypyrrole worked as source and drain electrodes

H. Koezuka, A. Tsumura, H. Fuchigami, and K. Kuramoto

Appl. Phys. Lett. 62, 1794 (1993); http://dx.doi.org/10.1063/1.109552 (3 pages) | Cited 22 times

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The field‐effect transistor has been fabricated, where polythiophene works as a semiconductor and a couple of polypyrrole layers act as a source and/or a drain electrode. The modulation ratio of the channel current with gate voltages has reached ca. 105, which is the largest one among organic FETs. This large modulation has been attributed to the depression of the channel current at no gate bias. It has been elucidated that the depression is caused by the barrier against hole transport formed inside the polythiophene layer and near the interface with polypyrrole.
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85.30.Tv Field effect devices
73.61.Ph Polymers; organic compounds
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Experimental proof for nanoparticle origin of photoluminescence in porous silicon layers

Margit Koós, István Pócsik, and Éva B. Vázsonyi

Appl. Phys. Lett. 62, 1797 (1993); http://dx.doi.org/10.1063/1.109553 (3 pages) | Cited 17 times

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A series of nonlinear phenomena in the excitation intensity dependence of photoluminescence (PL) was observed in porous silicon (PS) at room temperature. From a low level of excitation, the blue shift of the PL spectra was detected followed by complete saturation of the integrated PL intensity, without detectable change in the spectral position. This behavior may well be experimental proof of the nonparticle origin of PS light emission.
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78.55.Hx Other solid inorganic materials
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Observation of phonon‐plasmon coupled modes at the interface between ZnSe and semi‐insulating GaAs by micro‐Raman spectroscopy

M. Ichimura, A. Usami, T. Wada, Sz. Fujita, and Sg. Fujita

Appl. Phys. Lett. 62, 1800 (1993); http://dx.doi.org/10.1063/1.109554 (3 pages) | Cited 7 times

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We demonstrate that the nature of the interface between ZnSe and semi‐insulating GaAs can be studied by observing the phonon‐plasmon coupled mode by micro‐Raman spectroscopy. When the GaAs substrate is sulfur‐treated before the growth of ZnSe, the phonon‐plasmon coupled mode is clearly observed in micro‐Raman spectra. The plasmon is believed to be composed of electrons excited by the focused laser beam used in the micro‐Raman measurement. The coupled mode is weak when the substrate is not sulfur‐treated. The reduction in the coupled‐mode intensity will be due to interface states which widen the depletion layer and shorten the lifetime of excess carriers.
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73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
78.30.Fs III-V and II-VI semiconductors

Bias assisted etching of diamond in a conventional chemical vapor deposition reactor

B. R. Stoner, G. J. Tessmer, and D. L. Dreifus

Appl. Phys. Lett. 62, 1803 (1993); http://dx.doi.org/10.1063/1.109555 (3 pages) | Cited 18 times

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A novel technique for selectively etching diamond films is presented. This letter describes a technique by which diamond may be etched in a conventional plasma assisted chemical vapor deposition (CVD) reactor at rates comparable to those reported for both electron cyclotron resonance and reactive ion etching techniques. This technique involves negatively biasing the diamond film, while it is immersed in a mostly hydrogen containing plasma. Negative dc bias assisted etching of CVD diamond films is performed in both microwave and dc plasma reactors over a wide range of temperatures and pressures. Speculation on the etching mechanisms is also included.
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81.65.-b Surface treatments
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Band‐gap narrowing in ordered Ga0.47In0.53As

D. J. Arent, M. Bode, K. A. Bertness, Sarah R. Kurtz, and J. M. Olson

Appl. Phys. Lett. 62, 1806 (1993); http://dx.doi.org/10.1063/1.109640 (3 pages) | Cited 30 times

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We report the first observation of band‐gap energy reduction in Ga0.47In0.53As deposited on (100) InP by atmospheric pressure organometallic vapor phase epitaxy due to CuPt‐type ordering. A reduction of more than 65 meV in the band‐gap energy is observed for lattice‐matched samples that show strong CuPt‐like ordering by transmission electron microscopy. By comparison samples that show no CuPt‐like ordering diffraction signatures, do not have reduced band‐gap energies. Studies of the influence of growth parameters on the band‐gap energy indicate a U‐shaped dependence on the growth temperature with a minimum around 550 °C and decreasing band‐gap energies with increasing growth rate (at a constant V/III ratio) over the range 0.5–4 μm/h.
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71.20.Nr Semiconductor compounds
71.20.Ps Other inorganic compounds
81.15.Kk Vapor phase epitaxy; growth from vapor phase

Effect of band structure on etch‐stop layers in the photoelectrochemical etching of GaAs/AlGaAs semiconductor structures

R. Khare, D. B. Young, G. L. Snider, and E. L. Hu

Appl. Phys. Lett. 62, 1809 (1993); http://dx.doi.org/10.1063/1.109556 (3 pages) | Cited 6 times

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We have examined the limitations on selectivity of thin dopant‐selective and band‐gap‐selective etch‐stop layers in the photoelectrochemical (PEC) etch process. The ultimate selectivity of one layer from an underlying layer is affected not only by differences in material composition, but also by the sequencing of the layers within the structure which will determine the distribution of the photogenerated carriers. Three semiconductor structures with variations in both doping and band gap were etched to demonstrate this effect. A He‐Ne laser (633 nm) and a tunable Ti/sapphire laser (690–830 nm) were used as light sources and a (1:20) HCl:H2O solution was the electrolyte.
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81.65.-b Surface treatments
82.50.-m Photochemistry
82.45.-h Electrochemistry and electrophoresis

Photoluminescence, Raman scattering, and infrared absorption studies of porous silicon

Y. H. Seo, H.‐J. Lee, H. I. Jeon, D. H. Oh, K. S. Nahm, Y. H. Lee, E.‐K. Suh, H. J. Lee, and Y. G. Kwang

Appl. Phys. Lett. 62, 1812 (1993); http://dx.doi.org/10.1063/1.109557 (3 pages) | Cited 15 times

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Porous silicon layers prepared by anodic dissolutions of silicon wafers in aqueous HF solutions reveal either crystalline phase or intermediate phase between microcrystalline and amorphous phases, depending on the anodization conditions. The configurations of hydrogen and oxygen atoms near the surface of microstructures are directly related to the light emitting characteristics of porous silicon layers. We observed that oxidation leads to the shifts of SiHn stretching modes to higher frequencies and enhanced photoluminescence intensity, which can be correlated with a charge transfer within O—Si—H bonds. We also observed that chemical treatments in trichloroethylene have similar effects as thermal oxidation.
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78.55.Hx Other solid inorganic materials
81.65.-b Surface treatments
78.30.Hv Other nonmetallic inorganics

Tunneling effective mass in hydrogenated amorphous silicon

J. M. Shannon and K. J. B. M. Nieuwesteeg

Appl. Phys. Lett. 62, 1815 (1993); http://dx.doi.org/10.1063/1.109558 (3 pages) | Cited 23 times

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The tunneling effective mass of electrons in undoped a‐Si:H has been determined from measurements on Schottky diodes operating with high reverse fields. Under these conditions, the change of current with electric field is a sensitive function of effective mass. The tunneling effective mass was measured to be 0.09±0.02 me for a range of different samples giving a tunneling constant of ≊40 Å.
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73.40.Sx Metal-semiconductor-metal structures
73.40.Gk Tunneling
72.80.Ng Disordered solids
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor

High performance strained InGaAs/AlGaAs buried‐heterostructure quantum‐well lasers fabricated by in situ etching and regrowth

Naresh Chand, N. K. Dutta, S. N. G. Chu, A. V. Syrbu, A. Z. Mereutza, and V. P. Yakovlev

Appl. Phys. Lett. 62, 1818 (1993); http://dx.doi.org/10.1063/1.109559 (3 pages) | Cited 2 times

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We report a novel method for growth and fabrication of high performance strained InGaAs/AlGaAs quantum‐well buried‐heterostructure (BH) lasers. The method involves growth of the laser structure by molecular beam epitaxy, mesa formation by in situ melt etching using SiO2 stripes as a mask, and regrowth of p−‐p‐n AlGaAs isolating layers by liquid phase epitaxy. The method allows etching, preservation of high quality sidewalls, regrowth, and planarization in one step with negligible thermal disordering. Compared to ridge waveguide lasers, the BH lasers so fabricated have significantly lower threshold current, higher power output, higher temperature operation, lower cavity losses, and kink‐free light‐current (L‐I) characteristics, as expected. A cw power of 150 mW/facet at 986 nm was measured from a 400‐μm‐long BH laser with 11 μm active stripe width. A minimum threshold current of 2.5 mA was measured for lasers with 3.0 μm active width and 300–400 μm cavity length. The L‐I characteristics of 500‐, 800‐, and 1300‐μm‐long lasers with 3.0 μm active width were linear up to the currents corresponding to a current density of 10 kA cm−2. At higher current densities, a sublinear increase of power with current was observed. Stable fundamental transverse mode operation was obtained up to 100 mW emitted power.
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42.55.Px Semiconductor lasers; laser diodes
42.60.-v Laser optical systems: design and operation
68.55.-a Thin film structure and morphology

Gas phase reactions of trimethylamine alane in low pressure organometallic vapor phase epitaxy of AlGaAs

B. L. Pitts, D. T. Emerson, and J. R. Shealy

Appl. Phys. Lett. 62, 1821 (1993); http://dx.doi.org/10.1063/1.109560 (3 pages) | Cited 4 times

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We have investigated the effects of gas phase reactions between trimethylamine alane (TMAA), triethylgallium (TEG), and arsine on AlxGa1−xAs films grown by low pressure organometallic vapor phase epitaxy. The reactor used in this study provides for independent observation of the effects of TEG‐TMAA and TMAA‐arsine gas phase reactions. Gas phase reactions involving TMAA and TEG result in the formation of nonvolatile compounds upstream, which condense on the reactor wall, resulting in a reduction of growth rate and a degradation of the deposition uniformity. The TMAA‐arsine reaction produces a compositional dependence on the gas phase stoichiometry (V/III ratio). Both of these effects are more severe for higher TMAA fluxes. High quality AlGaAs with excellent thickness and compositional uniformity was produced by spatially separating the TMAA and TEG in the gas phase which minimizes the parasitic reactions.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)

YBa2Cu3O7 thin film SQUID gradiometer for biomagnetic measurements

Y. Tavrin, Y. Zhang, M. Mück, A. I. Braginski, and C. Heiden

Appl. Phys. Lett. 62, 1824 (1993); http://dx.doi.org/10.1063/1.109561 (3 pages) | Cited 43 times

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Low‐noise rf SQUID washers fabricated from YBa2Cu3O7 epitaxial thin films have been used to construct a first‐order electronic gradiometer operating at 77 K and suitable for biomagnetic measurements. Mechanical adjustment of the two‐SQUID gradiometric setup made it possible to attenuate signals due to far magnetic field sources by three orders of magnitude. A magnetic field resolution of ≤280 fT/Hz1/2 above 2 Hz was attained through the use of large flux focusers. The fine structure of human heart magnetocardiograms was recorded in unshielded space. In a shielded room, magnetoencephalograms were obtained. The system was used to obtain new data on auditory evoked cortical response.
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85.25.Dq Superconducting quantum interference devices (SQUIDs)
87.80.-y Biophysical techniques (research methods)
87.50.C- Static and low-frequency electric and magnetic fields effects
74.72.-h Cuprate superconductors

Direct observation of gold valence change as a function of oxygen stoichiometry in YBa2Cu3−yAuyO7−δ

M. Eibschütz, M. E. Lines, W. M. Reiff, B. van Dover, J. V. Waszczak, S. Zahurak, and R. J. Felder

Appl. Phys. Lett. 62, 1827 (1993); http://dx.doi.org/10.1063/1.109562 (3 pages) | Cited 6 times

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A study of the Au197 Mössbauer resonance is reported as a function of oxygen stoichiometry for gold‐doped YBa2Cu3O7−δ. Three separate Mössbauer features are identified and correspond respectively to gold metal particles, Au3+ in a square‐planar Cu(1) site, and Au+ in a two‐ligand c‐axis coordinated Cu(1) site. All the gold successfully incorporated into the 123‐structure is trivalent at full oxygenation (O7.02) but is reduced as a function of decreasing oxygen content until only monovalent gold remains at the orthorhombic to tetragonal transition (≊O6.4). A significant fraction of the Au3+ in the oxygenated sample resides near grain boundaries and is precipitated as gold particles upon reduction. The observation of monovalent gold in the reduced sample is the first report of the existence of Au+ with uniquely oxygen coordination for any material.
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74.72.-h Cuprate superconductors
74.62.Dh Effects of crystal defects, doping and substitution
76.80.+y Mössbauer effect; other γ-ray spectroscopy

Wide temperature scaling law of the secondary peak observed in magnetization curves of single crystals (La,Sr)2CuO4

T. Kobayashi, Y. Nakayama, K. Kishio, T. Kimura, K. Kitazawa, and K. Yamafuji

Appl. Phys. Lett. 62, 1830 (1993); http://dx.doi.org/10.1063/1.109563 (3 pages) | Cited 19 times

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Magnetization curves of single crystals (La1−xSrx)2CuO4 with various Sr contents were measured. A distinct increase of magnetization with increasing applied field was observed in Sr overdoped compositions, when the magnetic field was applied perpendicular to the CuO2 plane. The field, Bpk , where magnetization showed a maximum value, was strongly dependent on temperature. Its dependence was expressed by a universal relation √Bpk = c(x)[1−T/Tc(x)] over a wide temperature range; between 4.2 K and Tc. Possible mechanisms which give rise to the observed distinct secondary peak effect are discussed.
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74.25.Ha Magnetic properties including vortex structures and related phenomena
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
74.72.-h Cuprate superconductors

Magnetic properties of LaNiO3 films and Josephson characteristics of Y1Ba2Cu3O7−y/LaNiO3/Au/Ag/Pb junctions

Masayuki Sagoi, Teruyuki Kinno, Jiro Yoshida, and Koichi Mizushima

Appl. Phys. Lett. 62, 1833 (1993); http://dx.doi.org/10.1063/1.109564 (3 pages) | Cited 10 times

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A conductive perovskite oxide, LaNiO3, has been examined for the application to the normal layer for superconductor‐normal metal‐superconductor junctions for the first time. LaNiO3 films showed resistivity as low as 1.5×10−4 Ω cm. Pauli paramagnetism dominated in the film. The susceptibility measured was 0.9×10−6 emu/Oe g. Boundaries between the Y1Ba2Cu3O7−y and LaNiO3 layers were found to be abrupt in a Y1Ba2Cu3O7−y/LaNiO3 multilayer by transmission electron microscopy (TEM) observation. The coherence length in LaNiO3 was estimated to be 30–70 Å from characteristics of the Y1Ba2Cu3O7−y/LaNiO3/Au/Ag/Pb junctions. The value was comparable to the dirty limit coherence length of (ℏD/2πkBT)1/2 of the conventional theory (D; the diffusion constant in LaNiO3).
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74.45.+c Proximity effects; Andreev reflection; SN and SNS junctions
74.50.+r Tunneling phenomena; Josephson effects
75.70.-i Magnetic properties of thin films, surfaces, and interfaces

In‐plane epitaxial alignment of YBa2Cu3O7−x films grown on silver crystals and buffer layers

J. D. Budai, R. T. Young, and B. S. Chao

Appl. Phys. Lett. 62, 1836 (1993); http://dx.doi.org/10.1063/1.109565 (3 pages) | Cited 38 times

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Superconducting YBa2Cu3O7−x (YBCO) films were grown by laser ablation on Ag(001), Ag(110), and Ag(111) single‐crystal surfaces. X‐ray diffraction measurements showed that, in all cases, the films were aligned with specific in‐plane epitaxial orientation with respect to the crystallographic axes of the substrate. The observed orientations were consistent with predictions of near‐coincident site lattice models of the YBCO‐Ag interface. This technique for achieving three‐dimensional film alignment was extended to include a Ag epitaxial buffer layer on mica in place of a bulk Ag crystal. In‐plane epitaxial alignment on metal substrates and buffer layers has important consequences in practical applications for inhibiting weak‐link behavior caused by high‐angle grain boundaries.
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68.55.-a Thin film structure and morphology
81.15.Fg Pulsed laser ablation deposition
74.78.-w Superconducting films and low-dimensional structures
74.72.-h Cuprate superconductors

Electron holography in the study of the leakage field of magnetic force microscope sensor tips

G. Matteucci, M. Muccini, and U. Hartmann

Appl. Phys. Lett. 62, 1839 (1993); http://dx.doi.org/10.1063/1.109566 (3 pages) | Cited 9 times

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Electron holography is applied to the investigation of the leakage magnetic field produced by sharp ferromagnetic probes employed for magnetic force microscopy. Using the double exposure technique, interference fringes were obtained which show a good qualitative agreement with calculations based on a macroscopic dipole model for the sensor tips. Magnetic flux measurements are possible through the evaluation of the phase difference in the simulated map of the dipole field.
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68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Ps Atomic force microscopy (AFM)
68.37.Rt Magnetic force microscopy (MFM)
68.37.Uv Near-field scanning microscopy and spectroscopy
75.70.Kw Domain structure (including magnetic bubbles and vortices)

Influence of deposition temperature on giant magnetoresistance of Fe/Cr multilayers

S. S. P. Parkin and B. R. York

Appl. Phys. Lett. 62, 1842 (1993); http://dx.doi.org/10.1063/1.109542 (3 pages) | Cited 16 times

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The giant magnetoresistance effect ΔR/R in magnetron‐sputter deposited Fe/Cr multilayers is shown to depend strongly on deposition temperature. The largest values of ΔR and magnetoresistance are found in structures deposited at ≂125 °C. Structures deposited at lower (≂30 °C) or higher (≂200 °C) temperatures exhibit lower ΔR and ΔR/R values. Low angle x‐ray reflectivity and rocking curve data show that all the structures have well defined layers. However the largest giant MR values are found in structures which have the lowest high field resistivities, R, the longest structural coherence lengths and the narrowest (110) rocking curve widths. These results suggest that more perfect structures have intrinsically higher giant magnetoresistance.
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75.70.-i Magnetic properties of thin films, surfaces, and interfaces
72.15.Gd Galvanomagnetic and other magnetotransport effects
81.15.Cd Deposition by sputtering
68.35.B- Structure of clean surfaces (and surface reconstruction)

Microwave measurement of the dielectric constant of Sr0.5Ba0.5TiO3 ferroelectric thin films

K. R. Carroll, J. M. Pond, D. B. Chrisey, J. S. Horwitz, R. E. Leuchtner, and K. S. Grabowski

Appl. Phys. Lett. 62, 1845 (1993); http://dx.doi.org/10.1063/1.109522 (3 pages) | Cited 65 times

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Measurement of the relative dielectric constant of a Sr0.5Ba0.5TiO3 (SBT) thin film is presented as a function of electric field strength and temperature over a broad frequency range using a microstrip transmission line. The transmission line was fabricated from a trilayer structure where the SBT film, grown by pulsed laser deposition, was bounded by silver and platinum metallization layers. Such structures involving ferroelectric films could be useful for microwave applications because of the substantially smaller bias voltages (≊1–10 V) compared to those required for bulk material. The SBT film was found to exhibit a dielectric constant of ≊120–250 and a large electric field modulation of ≊50% at 200 kV/cm. These properties of the material as well as the Curie temperature are compared to those of bulk SBT.
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77.80.-e Ferroelectricity and antiferroelectricity
77.55.-g Dielectric thin films
84.40.-x Radiowave and microwave (including millimeter wave) technology
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
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