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26 Jun 1995

Volume 66, Issue 26, pp. 3543-3688

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Electron and hole mobility in tris(8‐hydroxyquinolinolato‐N1,O8) aluminum

R. G. Kepler, P. M. Beeson, S. J. Jacobs, R. A. Anderson, M. B. Sinclair, V. S. Valencia, and P. A. Cahill

Appl. Phys. Lett. 66, 3618 (1995); http://dx.doi.org/10.1063/1.113806 (3 pages) | Cited 7 times

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We have measured the drift mobility of electrons and holes in thin, vapor‐deposited films of tris(8‐hydroxyquinolinolato‐N1,O8) aluminum using a time of flight photoconductivity technique. The drift of mobility of both carriers is dispersive and strongly electric field and temperature dependent. At ambient temperature and an electric field of 4×105 V cm−1, the effective mobility of electrons and holes is 1.4×10−6 and 2×10−8 cm2 V−1 s−1, respectively, in a 400 nm thick sample. © 1995 American Institute of Physics.
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73.50.Pz Photoconduction and photovoltaic effects
73.61.Ph Polymers; organic compounds

Nanoprobe‐induced electrostatic lateral quantization in near‐surface resonant‐tunneling heterostructures

M. D. Taylor, G. C. Wetsel, S. E. McBride, R. C. Brown, W. R. Frensley, A. C. Seabaugh, Y.‐C. Kao, and E. A. Beam

Appl. Phys. Lett. 66, 3621 (1995); http://dx.doi.org/10.1063/1.113807 (3 pages) | Cited 6 times

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We report experimental and theoretical evidence for electrostatic lateral confinement induced by a nanoprobe. The lateral confinement is manifest as oscillations of the differential conductance of a near‐surface resonant‐tunneling heterostructure in air at room temperature. © 1995 American Institute of Physics.
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73.40.Gk Tunneling
81.07.-b Nanoscale materials and structures: fabrication and characterization
81.16.-c Methods of micro- and nanofabrication and processing
85.35.-p Nanoelectronic devices
85.30.De Semiconductor-device characterization, design, and modeling

Doping of chemically deposited intrinsic CdS thin films to n type by thermal diffusion of indium

P. J. George, A. Sánchez, P. K. Nair, and M. T. S. Nair

Appl. Phys. Lett. 66, 3624 (1995); http://dx.doi.org/10.1063/1.113808 (3 pages) | Cited 21 times

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CdS thin films deposited from chemical bath containing citratocadmium(II) and thiourea are intrinsic and highly photosensitive. In the present letter, we discuss the conversion of such films to n type by thermal diffusion of indium from an evaporated 50 nm indium film deposited on the CdS thin film. The process which takes place in the temperature range of 250 °C–350 °C involves the formation of an In2O3 surface layer which acts as a barrier preventing the outdiffusion of indium. This allows indium to diffuse into the CdS film and results in an indium‐doped CdS thin film. The electrical conductivity of such films is about 300 Ω−1 cm−1. All beneficial optical properties of chemically deposited CdS thin films for application as a window material in heterojunction optoelectronic devices are retained. © 1995 American Institute of Physics.
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73.61.Ga II-VI semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Controlled manipulation of nanoparticles with an atomic force microscope

T. Junno, K. Deppert, L. Montelius, and L. Samuelson

Appl. Phys. Lett. 66, 3627 (1995); http://dx.doi.org/10.1063/1.113809 (3 pages) | Cited 129 times

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We report on the application of the atomic force microscope (AFM) to manipulate and position nanometer‐sized particles with nanometer precision. The technique, which can be regarded as a nanometer‐scale analogy to atomic level manipulation with the scanning tunneling microscope, allowed us to form arbitrary nanostructures, under ambient conditions, by controlled manipulation of individual 30 nm GaAs particles. A whole new set of nanodevices can be fabricated particle‐by‐particle for studies of quantum effects and single electron tunneling. We also demonstrate a method, based on the AFM manipulation, to determine the true lateral dimensions of nano‐objects, in spite of the tip‐sample convolution. © 1995 American Institute of Physics.
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81.07.-b Nanoscale materials and structures: fabrication and characterization
81.16.-c Methods of micro- and nanofabrication and processing
85.35.-p Nanoelectronic devices
07.79.Lh Atomic force microscopes

Direct evidence for the existence of exciton bound on Yb3+ ion in In(P,As) crystals

A. Kozanecki and A. Szczerbakow

Appl. Phys. Lett. 66, 3630 (1995); http://dx.doi.org/10.1063/1.114122 (3 pages) | Cited 2 times

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Temperature dependence of luminescence was measured in InPxAs1−x:Yb crystals (x=7% and 12%) and in reference undoped material (x=8%). A simple correlation between Yb doping and the number of thermally activated bands in the near‐band‐edge spectral region of In(P,As) alloys was found. A new luminescence band located at ∼25 meV below the free‐carrier, band‐to‐band emission was observed in Yb‐doped alloys only. A one‐to‐one correspondence between the appearance of this band and the quenching of the intra‐4f‐shell photoluminescence of Yb3+ ions is shown. These observations are taken as direct evidence for participation of excitons bound on Yb3+ ion in the excitation and quenching processes of the 4f shell. © 1995 American Institute of Physics.  
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78.55.Cr III-V semiconductors
71.35.-y Excitons and related phenomena

Optical phonons in a quantum well containing monolayers

B. K. Ridley

Appl. Phys. Lett. 66, 3633 (1995); http://dx.doi.org/10.1063/1.114123 (3 pages) | Cited 8 times

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The continuum theory of optical‐mode hybrids in multilayered structures is applied to the case of a quantum well containing a centrally placed monolayer of a semiconductor whose optical frequencies are very different from those of the host. It is shown that antisymmetric modes are strongly modified whereas symmetric modes are not modified at all. As a consequence, the intersubband scattering rate is expected to be reduced. © 1995 American Institute of Physics.
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63.20.D- Phonon states and bands, normal modes, and phonon dispersion
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
68.35.Ja Surface and interface dynamics and vibrations

Twenty‐four percent efficient silicon solar cells with double layer antireflection coatings and reduced resistance loss

J. Zhao, A. Wang, P. Altermatt, and M. A. Green

Appl. Phys. Lett. 66, 3636 (1995); http://dx.doi.org/10.1063/1.114124 (3 pages) | Cited 83 times

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Significant performance increase for silicon solar cells is reported. This has been achieved by a combination of several mechanisms. One is the reduction of recombination at cell surfaces using atomic hydrogen passivation of silicon/silicon dioxide interfaces. Joule resistive losses in the cell have been reduced by a process which allows different thickness for fine and coarse features in the top cell metallization. Finally, reflection losses have been reduced by the use of a double layer antireflection coating. For successful incorporation, this required the development of techniques for growing the surface passivating oxide very thin, without reducing its passivation qualities. The cells display a monochromatic light energy conversion efficiency of 46.3% for 1.04 μm wavelength light, also the highest ever for a silicon devices. © 1995 American Institute of Physics.  
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84.60.Jt Photoelectric conversion
72.40.+w Photoconduction and photovoltaic effects

Measuring the tensor nature of stress in silicon using polarized off‐axis Raman spectroscopy

G. H. Loechelt, N. G. Cave, and J. Menéndez

Appl. Phys. Lett. 66, 3639 (1995); http://dx.doi.org/10.1063/1.114125 (3 pages) | Cited 18 times

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Polarized off‐axis Raman spectroscopy is a technique for measuring the complete tensor nature of stress fields in semiconductors. By combining incident light tilted away from the normal axis with polarization of the incident and scattered beams, any Raman‐active optical phonon mode can be selectively studied. Once the frequencies and intensities of these phonons are measured, the complete stress tensor can be uniquely determined. This technique has been applied macroscopically to mechanically deformed silicon wafers under biaxial tension. The results of this approach compare favorably with the stress calculated by means of the theory of elasticity. © 1995 American Institute of Physics.
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62.20.D- Elasticity
78.30.Hv Other nonmetallic inorganics

Evolution of strain relaxation in step‐graded SiGe/Si structures

P. M. Mooney, J. L. Jordan‐Sweet, J. O. Chu, and F. K. LeGoues

Appl. Phys. Lett. 66, 3642 (1995); http://dx.doi.org/10.1063/1.114126 (3 pages) | Cited 28 times

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Strain relaxation in a series of step‐graded SiGe/Si structures has been quantitatively investigated by high‐resolution x‐ray diffraction measurements. We show that beyond a critical thickness, dislocations nucleate continuously as layers with higher Ge mole fraction are added to the structure and that the mismatch strain at which nucleation occurs is therefore essentially constant. It had been found empirically that a lower growth temperature is required to suppress roughening of layers with higher Ge mole fraction, even in graded structures. We prove that this is not because the strain increases, but rather because of the lower melting temperature of layers with higher Ge content. © 1995 American Institute of Physics.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.Dd Experimental determination of defects by diffraction and scattering

Step bunching in chemical vapor deposition of 6H– and 4H–SiC on vicinal SiC(0001) faces

Tsunenobu Kimoto, Akira Itoh, and Hiroyuki Matsunami

Appl. Phys. Lett. 66, 3645 (1995); http://dx.doi.org/10.1063/1.114127 (3 pages) | Cited 41 times

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Step bunching and terrace widening on 6H– and 4H–SiC epilayers on vicinal {0001} faces have been studied with atomic force microscopy (AFM) and transmission electron microscopy (TEM). Macroscopically, hill‐and‐valley structures are observed on off‐oriented (0001)Si faces, whereas surfaces are rather flat on off‐oriented (0001)C faces. High‐resolution TEM analysis revealed that 3 bilayer‐height steps are dominant on 6H–SiC and 4 bilayer‐height steps on 4H–SiC. The distribution of step height and terrace width are also investigated. © 1995 American Institute of Physics.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
68.35.B- Structure of clean surfaces (and surface reconstruction)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Millimeter wave distributed metal‐semiconductor‐metal photodetectors

E. H. Böttcher and D. Bimberg

Appl. Phys. Lett. 66, 3648 (1995); http://dx.doi.org/10.1063/1.114128 (3 pages) | Cited 15 times

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We propose and analyze a method for distributed photodetection using waveguide‐coupled metal‐semiconductor‐metal (MSM) photodetectors. The electrode configuration is a coplanar strip waveguide capacitively loaded with the interdigitated MSM structure. The slow wave character of this structure allows for matching the velocity of the guided electrical wave to that of the optical waveguide resulting in virtually capacitance‐free photodetection. In the context of actual device structures and operating conditions, the bandwidth limitation due to velocity mismatch and the influence of transmission line loss and dispersion on the high‐frequency response are calculated and is found to be close to 1 THz. Thus, the detector structure is suitable for fully exploiting the transit‐time‐limited bandwidth potential of ≥200 GHz which is attainable by using interdigitated electrodes with ≤0.1 μm spacing and width. © 1995 American Institute of Physics.
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73.40.Sx Metal-semiconductor-metal structures
85.60.Gz Photodetectors (including infrared and CCD detectors)

High speed metal‐semiconductor‐metal photodetector manufactured on GaAs by low‐temperature photoassisted metalorganic chemical vapor deposition

K. S. Boutros, J. C. Roberts, S. M. Bedair, T. F. Carruthers, and M. Y. Frankel

Appl. Phys. Lett. 66, 3651 (1995); http://dx.doi.org/10.1063/1.114129 (3 pages) | Cited 3 times

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We report on the photoassisted metalorganic chemical vapor deposition (MOCVD) of high resistivity gallium‐arsenide at low‐temperature (LT‐GaAs). The as‐grown GaAs exhibits a resistivity of ∼106 Ω cm and has been used as the active layer of a metal‐semiconductor‐metal (MSM) Schottky‐barrier photodetector. The impulse response of the detector is 4 ps with a dark current of 4 nA at a bias of 2 V. These results are comparable to those obtained from LT‐GaAs grown by molecular beam epitaxy (MBE). © 1995 American Institute of Physics.
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73.40.Sx Metal-semiconductor-metal structures
85.60.Gz Photodetectors (including infrared and CCD detectors)
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Silicon‐on‐insulator produced by helium implantation and thermal oxidation

V. Raineri and S. U. Campisano

Appl. Phys. Lett. 66, 3654 (1995); http://dx.doi.org/10.1063/1.114130 (3 pages) | Cited 9 times

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A novel technique that produces a high quality low cost silicon‐on‐insulator is described. The method takes advantage of the formation of a buried porous layer in silicon implanted with light ions. Trenches are then formed in such a way that O2 can be transported into the cavities. Finally, an oxidation in dry O2 produces a buried oxide layer. Helium ions at energies of 40 or 300 keV and fluences up to 2×1017/cm2 were uniformly implanted into 5 in. silicon wafers. The oxidations were performed in a rapid thermal oxidation system by using dry O2 at a temperature of about 1000 °C and for times up to 5 min. Transmission electron microscopy on cross sectional samples revealed that high quality buried oxide layers were formed and defect free single crystal silicon remained at the surface. © 1995 American Institute of Physics.
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85.40.Hp Lithography, masks and pattern transfer
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
61.72.uf Ge and Si

Lattice relaxation in InxAl1−xAs/GaAs heterostructure grown on exact oriented and misoriented GaAs substrates

Jong‐Hyeob Baek, Bun Lee, Meeyoung Yoon, El‐Hang Lee, and Chang Soo Kim

Appl. Phys. Lett. 66, 3657 (1995); http://dx.doi.org/10.1063/1.114131 (3 pages) | Cited 1 time

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We have examined lattice relaxation properties of 2 μm thick InxAl1−xAs epitaxial layers grown simultaneously on a (100) exact oriented GaAs substrate and on a 2° misoriented GaAs substrate by low pressure metalorganic chemical vapor deposition method. Double crystal x‐ray diffractometry has been used to determine the alloy compositions at various azimuthal angles. As a result of (400) x‐ray rocking curve analysis, it was found that the full width at half‐maximum (FWHM) of x‐ray rocking curves for both samples were strongly dependent on the azimuthal angle, indicating that the lattice relaxation depended greatly on the substrate orientation. From the data of {511} asymmetric measurements for four different directions, the In contents of the epitaxial layers found were 24%. The In0.24Al0.76As epitaxial layers grown on an exact oriented substrate and on a misoriented substrate both showed 82% relaxation, which was a larger value in comparison with the similarly mismatched InGaAs/GaAs heterostructure. The periodic FWHM of the x‐ray rocking curves shows that the anisotropy of residual strain was independent of the nominal substrate misoriented direction. For both types of substrate, it is most likely that the variation of the FWHM originates from asymmetric densities of misfit dislocation. © 1995 American Institute of Physics.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
61.05.cf X-ray scattering (including small-angle scattering)
61.05.cj X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.

Electron paramagnetic resonance study of luminescent stain etched porous silicon

M. Schoisswohl, J. L. Cantin, H. J. von Bardeleben, and G. Amato

Appl. Phys. Lett. 66, 3660 (1995); http://dx.doi.org/10.1063/1.114132 (3 pages) | Cited 9 times

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The defects and the morphology of stain etched porous Si of 60% to 70% porosity have been studied by electron paramagnetic resonance (EPR), scanning tunneling microscopy (STM), and Raman spectroscopy. The samples contain two pore phases with dimensions in the 1 and 10 nm range and present both visible and infrared photoluminescence. In as‐prepared and aged samples two paramagnetic defects are detected: the Pb center at (111) Si/SiO2 interfaces and the silicon dangling bond (DB) center. The neutral Pb center concentration is ≊1×1018 cm−3, which is an order of magnitude higher than in comparable anodically etched porous Si. The angular variation of the Pb EPR spectrum proves the predominant monocrystalline character of the material. The neutral DB center concentration of ≤1×1017 cm−3 indicates in agreement with the Raman results only for a low fraction (≊1 vol %) of disordered Si. Our results demonstrate that highly luminescent porous silicon, retaining the crystallinity of the substrate, can be prepared by stain etching. © 1995 American Institute of Physics.
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78.55.Hx Other solid inorganic materials
76.30.-v Electron paramagnetic resonance and relaxation

In situ fabrication of self‐aligned InGaAs quantum dots on GaAs multiatomic steps by metalorganic chemical vapor deposition

M. Kitamura, M. Nishioka, J. Oshinowo, and Y. Arakawa

Appl. Phys. Lett. 66, 3663 (1995); http://dx.doi.org/10.1063/1.114133 (3 pages) | Cited 82 times

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Self‐alignment of InGaAs quantum dots was achieved by growing the quantum dots on the multiatomic steps in metalorganic chemical vapor deposition. In this technique, first GaAs epilayer with multiatomic step structures along straight lines was grown on a vicinal GaAs substrate under appropriate growth conditions. Then, the InGaAs quantum dots were grown selectively on the multiatomic step edges using strain effects. This growth technique results in spontaneously aligned InGaAs quantum dots without any preprocessing technique prior to the growth. © 1995 American Institute of Physics.
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68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Single electron charging at temperatures above 4 K in ultrasmall lateral quantum dots patterned on shallow GaAs/AlGaAs heterostructures

Z. Borsosfoldi, M. Rahman, I. A. Larkin, A. R. Long, J. H. Davies, J. M. R. Weaver, M. C. Holland, and J. G. Williamson

Appl. Phys. Lett. 66, 3666 (1995); http://dx.doi.org/10.1063/1.114134 (3 pages) | Cited 5 times

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We demonstrate single electron charging in fully controllable nanoscale quantum devices at temperatures above 4 K. Hitherto, single electron devices operating at ‘‘high’’ temperatures have been two‐terminal, having no control electrode, whereas fully tunable structures such as quantum dots have only shown charging effects at temperatures of 4 K or less. We have fabricated ultrasmall quantum dots on modulation doped heterostructures where the two‐dimensional electron gas is less than 30 nm from the surface. Dots with lithographic diameter 150 nm show Coulomb oscillations up to temperatures of 7 K. Higher temperature operation allows potential applications to be considered without the need, for example, of a dilution fridge. © 1995 American Institute of Physics.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.40.Gk Tunneling

How methanol affects the surface of blue and red emitting porous silicon

J. M. Rehm, G. L. McLendon, L. Tsybeskov, and P. M. Fauchet

Appl. Phys. Lett. 66, 3669 (1995); http://dx.doi.org/10.1063/1.114135 (3 pages) | Cited 27 times

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The effects of liquid methanol on the photoluminescence intensity and FTIR spectra of red and blue emitting porous silicon were investigated. Hydrogen passivated red emitting samples exhibit quenching and recovery of photoluminescence intensity and broadening of the Si‐Hx stretch bands upon exposure to liquid methanol. Oxygen passivated red emitting samples exhibit no photoluminescence quenching. The sensitivity of the red emitting sample is due to the microstructure of porous silicon at the surface and the ability of methanol to penetrate the pores. The blue photoluminescence of thermally oxidized samples is quenched upon exposure to methanol. This is attributed to the solvent’s ability to change the surface passivation which modifies existing traps and introduces competitive recombination channels for electrons. © 1995 American Institute of Physics.
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78.66.Li Other semiconductors
78.55.Hx Other solid inorganic materials

Tightly confined one‐dimensional states in T‐shaped GaAs edge quantum wires with AlAs barriers

T. Someya, H. Akiyama, and H. Sakaki

Appl. Phys. Lett. 66, 3672 (1995); http://dx.doi.org/10.1063/1.114136 (2 pages) | Cited 23 times

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We have designed and prepared a T‐shaped GaAs edge quantum wire (T‐QWR) structure with AlAs barriers by cleaved edge overgrowth method. Three photoluminescence (PL) peaks have been observed and their origins are identified using the spatially resolved PL technique. The effective binding energy of carriers in this T‐QWR is precisely determined as the energy spacing between T‐QWRs and the adjacent QWs. When the well width of constituent QWs was 5 nm, the effective binding energy is found to be as large as 35 meV, which is far beyond the thermal energy kT at room temperature. © 1995 American Institute of Physics.
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73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
78.66.Fd III-V semiconductors

Electrically tunable coplanar transmission line resonators using YBa2Cu3O7−x/SrTiO3 bilayers

A. T. Findikoglu, Q. X. Jia, I. H. Campbell, X. D. Wu, D. Reagor, C. B. Mombourquette, and D. McMurry

Appl. Phys. Lett. 66, 3674 (1995); http://dx.doi.org/10.1063/1.114137 (3 pages) | Cited 68 times

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We have prepared electrically tunable microwave resonators incorporating superconducting YBa2Cu3O7−x (YBCO) and paraelectric SrTiO3 (STO) layers on LaAlO3 substrates. The top YBCO layer for each sample was patterned into a 8 mm long coplanar transmission line with a 40 μm gap and a 20 μm center line width. The microwave transmission through the coplanar transmission line exhibits resonances corresponding to standing microwaves along the coplanar transmission line. These resonances are modulated by applying a bias voltage between the center line and the ground planes. Samples with a 0.5 μm thick (2 μm thick) bottom STO layer show, for a resonance at around 8 GHz (5 GHz), a frequency modulation of about 4% (24%) and a quality factor Q of about 200 (50) under 100 V bias at 80 K. © 1995 American Institute of Physics.
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74.25.N- Response to electromagnetic fields
74.78.-w Superconducting films and low-dimensional structures
85.25.Qc Superconducting surface acoustic wave devices and other superconducting devices

Detection of new superconductors using phase‐spread alloy films

D. Lederman, D. C. Vier, D. Mendoza, J. Santamaría, S. Schultz, and Ivan K. Schuller

Appl. Phys. Lett. 66, 3677 (1995); http://dx.doi.org/10.1063/1.114138 (3 pages) | Cited 7 times

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We describe an effective method for discovery of new superconductors, which combines phase‐spread alloy thin film preparation with a magnetic field modulated (MFM) microwave absorption technique. The MFM technique can detect superconductivity in YBa2Cu3O7−δ volumes as small as 5×10−11 cm3. As an illustration, PrxGd1−xBa2Cu3O7−δ thin films with varying x were simultaneously grown on the same substrate using a phase‐spread alloy technique. The onset temperature determined from the microwave absorption agrees with resistivity, Auger spectroscopy, and energy‐dispersive x‐ray microanalysis data. When phase‐spread Lax(NiB)1−xNy films (0<x<1) were grown at several different N partial pressures and temperatures, no superconductivity was detected except that of pure La. In contrast, superconductivity was detected in Yx(NiB)1−xCy films grown on MgO. © 1995 American Institute of Physics.
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74.78.-w Superconducting films and low-dimensional structures
74.25.F- Transport properties

Magneto‐optical and high resolution electron microscopy studies of flux pinning at grain boundaries in Bi2Sr2CaCu2Ox crystals

T. Egi, J. G. Wen, H. Kubota, J. Ricketts, and N. Koshizuka

Appl. Phys. Lett. 66, 3680 (1995); http://dx.doi.org/10.1063/1.114139 (3 pages) | Cited 5 times

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We have studied the flux pinning behavior of Bi2Sr2CaCu2Ox multicrystalline samples using a magneto‐optical flux observation method. When a magnetic field is applied parallel to the ab plane, we find low flux density regions at the intersections of small angle grain boundaries. The flux density distribution can be explained by considering both flux pinning at the small angle grain boundaries and the intrinsic pinning effect at the BiO layers. High resolution electron microscopy observations show that amorphous patches with columnar structure exist at the small angle grain boundaries (<20°), while other defects such as misfit dislocations and distorted microstructures appear at general grain boundaries. The fact that flux pinning only occurs at small angle grain boundaries (<20°) indicates that the columnar amorphous structures could act as flux pinning centers. © 1995 American Institute of Physics.
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74.72.-h Cuprate superconductors
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)

High‐frequency response of capacitors fabricated from fine grain BaTiO3 thin films

P. K. Singh, S. Cochrane, W.‐T. Liu, K. Chen, D. B. Knorr, J. M. Borrego, E. J. Rymaszewski, and T.‐M. Lu

Appl. Phys. Lett. 66, 3683 (1995); http://dx.doi.org/10.1063/1.114140 (3 pages) | Cited 7 times

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Fine grain BaTiO3 thin films with a grain size ranging between 100 and 1000 Å were deposited using the reactive partially ionized beam deposition technique at 550–600 °C. A metal/insulator/metal structure of these materials was fabricated and the dielectric response was measured up to 40 GHz using a network analyzer. It is shown that these films are not ferroelectric. However, these films show a dielectric relaxation in the frequency interval between several MHz and 1 GHz. We propose that this indicates a relaxation mechanism not related to the ferroelectric domain walls. © 1995 American Institute of Physics.
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84.32.Tt Capacitors
77.55.-g Dielectric thin films

Area‐selective formation of an organosilane monolayer on silicon oxide nanopatterns fabricated by scanning probe anodization

Hiroyuki Sugimura, Nobuyuki Nakagiri, and Nobuyuki Ichinose

Appl. Phys. Lett. 66, 3686 (1995); http://dx.doi.org/10.1063/1.114141 (3 pages) | Cited 19 times

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An organosilane monolayer was formed from a precursor vapor (trimethylchlorosilane, TMCS) onto the surface of silicon oxide (SiOx) nanopatterns surrounded by hydrogen‐terminated silicon (Si–H). The nanopattern was fabricated with a resolution of 20 nm by scanning probe anodization, that is, localized anodization induced beneath the tip of a scanning probe microscope. The area‐selectivity arises from the difference in the chemical reactivity of the vapor between the SiOx and Si–H surfaces. The TMCS‐coated SiOx patterns showed a resistivity to chemical etching with an aqueous solution of ammonium fluoride and hydrogen peroxide. Lateral force microscopy with an organosilane‐coated probe also indicated the presence of the monolayer on SiOx through a friction force contrast between the monolayer‐coated and uncoated regions. © 1995 American Institute of Physics.
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81.07.-b Nanoscale materials and structures: fabrication and characterization
81.16.-c Methods of micro- and nanofabrication and processing
85.35.-p Nanoelectronic devices
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
81.65.-b Surface treatments
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