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29 Sep 1997

Volume 71, Issue 13, pp. 1747-1892

Page 2 of 2 Pages Previous Page | Jump to Page

X-ray reciprocal space mapping of a (112) oriented HgTe/Hg0.1Cd0.9Te superlattice

M. Li, C. R. Becker, R. Gall, W. Faschinger, and G. Landwehr

Appl. Phys. Lett. 71, 1822 (1997); http://dx.doi.org/10.1063/1.119410 (3 pages) | Cited 5 times

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Strain in a HgTe/Hg0.1Cd0.9Te superlattice grown on (112)B Cd0.96Zn0.04Te substrate has been investigated by x-ray reciprocal space mapping. It is shown that the shear strain in the superlattice results in monoclinic unit cells, whereas the cubic symmetry of the substrate is retained. The reciprocal lattice points of the superlattice are shifted by the shear strain such that the conventional analysis fails to interpret them correctly. Instead, reciprocal space maps should be constructed for two azimuths in opposite directions and analyzed simultaneously in a coordinate system with nonorthogonal axes. The shear strain is obtained from the angle between the [mathmath1] directions of the superlattice and the substrate. After a position correction taking the measured shear strain into account, longitudinal strains are calculated with conventional methods. © 1997 American Institute of Physics.
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68.35.Gy Mechanical properties; surface strains
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
62.20.F- Deformation and plasticity

III–V based magnetic(GaMnAs)/nonmagnetic(AlAs) semiconductor superlattices

T. Hayashi, M. Tanaka, K. Seto, T. Nishinaga, and K. Ando

Appl. Phys. Lett. 71, 1825 (1997); http://dx.doi.org/10.1063/1.119411 (3 pages) | Cited 57 times

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III–V based magnetic (GaMnAs)/nonmagnetic(AlAs) semiconductor superlattices (SLs) have been grown by low-temperature molecular beam epitaxy. X-ray diffraction measurements show that the SLs have good crystalline quality and abrupt interfaces. The SLs having relatively wide (Ga,Mn)As layers ( ≥ 70 Å) are found to be ferromagnetic at low temperatures, while the SLs with narrow (Ga,Mn)As layers ( ⩽ 50 Å) are paramagnetic even at 2.0 K. Magneto-optic spectra have revealed that, due to the quantum confinement effect, the interband transition energy at Γ is blue shifted with decreasing the thickness of the (Ga,Mn)As and some subbands are formed. © 1997 American Institute of Physics.
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75.50.Pp Magnetic semiconductors
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.66.Fd III-V semiconductors
81.05.Ea III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.20.Ls Magneto-optical effects
75.20.Ck Nonmetals
75.50.Dd Nonmetallic ferromagnetic materials

Thermal fixing of refractive index gratings in a photorefractive polymer

Ning Cheng, Bogdan Swedek, and Paras N. Prasad

Appl. Phys. Lett. 71, 1828 (1997); http://dx.doi.org/10.1063/1.119412 (3 pages) | Cited 16 times

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A significant increase in storage time by thermal fixing of photorefractive (PR) gratings in a polymeric composite of poly-9-vinycarbazole, tricresyl phosphate, fullerene, and 4-N,N-diethylamino-β-nitrostyrene is demonstrated. The fixing of the volume holograms is created by quasifreezing the orientation of the linearly anisotropic chromophore molecules. The fixed PR gratings can be easily erased by elevating the sample’s temperature to the glass transition temperature of the composite. The readout of the thermally fixed first-order grating does not require the presence of an external electric field. © 1997 American Institute of Physics.
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42.40.Eq Holographic optical elements; holographic gratings
42.40.Ht Hologram recording and readout methods
42.70.Ln Holographic recording materials; optical storage media
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
64.70.P- Glass transitions of specific systems
64.70.Q- Theory and modeling of the glass transition

Self-limiting growth of GaAs surfaces on nonplanar substrates

G. Biasiol, F. Reinhardt, A. Gustafsson, and E. Kapon

Appl. Phys. Lett. 71, 1831 (1997); http://dx.doi.org/10.1063/1.119413 (3 pages) | Cited 14 times

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The growth of GaAs epitaxial layers by organometallic chemical vapor deposition on top of V-grooved substrates is found to exhibit a self-limiting behavior. As in the case of the self-limiting growth of AlGaAs on similar patterned substrates, the self-limiting GaAs profile exhibits characteristic crystallographic nanofacets. However, these facets are considerably broader than in typical, self-limiting AlGaAs profiles obtained at similar growth temperatures. Atomic force microscopy in air reveals the three-dimensional structure of the self-limiting GaAs surfaces, showing monolayer steps on the central (100) nanofacets and quasiperiodic modulation caused by step bunching on the side {311}A nanofacets. The width of the self-limiting GaAs V grooves can be reduced to less than 10 nm at sufficiently low growth temperatures, thus providing useful templates for growing, e.g., self ordered InGaAs/GaAs quantum wires. © 1997 American Institute of Physics.
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81.05.Ea III-V semiconductors
81.15.Kk Vapor phase epitaxy; growth from vapor phase
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
68.35.B- Structure of clean surfaces (and surface reconstruction)
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

The effect of reactive plasma etching on the transient enhanced diffusion of boron in silicon

Vittorio Privitera, Francesco Priolo, Giovanni Mannino, Salvatore Ugo Campisano, Alberto Carnera, Giuseppe Arena, and Corrado Spinella

Appl. Phys. Lett. 71, 1834 (1997); http://dx.doi.org/10.1063/1.119414 (3 pages) | Cited 8 times

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Silicon wafers oxidized and stripped by reactive plasma etching were implanted with 5 keV B, 1×1013/cm2. The transient enhanced diffusion of B, usually observed in samples which receive such implants over characteristic time scales, is strongly retarded in these plasma etched samples upon annealing at 800, 900, or 1000 °C, as measured by secondary ions mass spectrometry. These results suggest that the defects generated by the plasma etching procedure in the near surface region, represent an efficient sink against the flow of interstitials which cause the transient enhanced diffusion. A slow release of interstitials from this trapping immobile background occurs with characteristic time scales which are, however, a factor of 30–60 times higher than the usual lifetimes of transient diffusion. This release is characterized by an activation energy of 2.4 eV. These data are reported and their implication on shallow junction formation are discussed. © 1997 American Institute of Physics.
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66.30.J- Diffusion of impurities
81.65.Cf Surface cleaning, etching, patterning
61.72.uf Ge and Si
61.72.Cc Kinetics of defect formation and annealing
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
81.05.Cy Elemental semiconductors

Ionized donor bound excitons in GaN

B. Šantic, C. Merz, U. Kaufmann, R. Niebuhr, H. Obloh, and K. Bachem

Appl. Phys. Lett. 71, 1837 (1997); http://dx.doi.org/10.1063/1.119415 (3 pages) | Cited 36 times

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The temperature and excitation power dependence of a bound exciton photoluminescence line S with a localization energy Q = 11.5 meV has been studied in undoped and moderately Mg-doped wurtzite GaN of high resistivity. The data provide strong evidence that line S is due to recombination of excitons bound to ionized shallow donors. The consistency of this assignment with theoretical predictions is demonstrated. © 1997 American Institute of Physics.
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71.35.Cc Intrinsic properties of excitons; optical absorption spectra
72.80.Ey III-V and II-VI semiconductors
71.55.Eq III-V semiconductors
78.55.Cr III-V semiconductors
71.55.Jv Disordered structures; amorphous and glassy solids
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Optical property of a novel (111)-oriented quantum structure

Xiong Zhang, Soo-Jin Chua, Shijie Xu, Kok-Boon Chong, and Kentaro Onabe

Appl. Phys. Lett. 71, 1840 (1997); http://dx.doi.org/10.1063/1.119416 (3 pages) | Cited 1 time

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A novel hetero tensile-unstrained-tensile-unstrained-tensile (t-u-t-u-t) quantum structure, which consists of multiple quantum wells in the unstrained (u) regions, lattice matched to a (111)-oriented substrate, and sandwiched between tensile-strained epitaxial layers (t), is proposed. The energy band configuration modified by the strain-induced piezoelectric field and the distribution of the built-in internal electric field within this hetero t-u-t-u-t quantum structure were theoretically deduced and found to be consistent with the experimental results. It was demonstrated that some nonlinear optical properties such as the energy blue shift observed in the excitation-power-dependent photoluminescence spectra are strongly dependent on the distribution of the strain-induced built-in electric field within this quantum structure and quite comparable to the analogous values for the existing quantum structures. © 1997 American Institute of Physics.
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78.66.Fd III-V semiconductors
42.65.-k Nonlinear optics
78.55.Cr III-V semiconductors
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
77.65.Ly Strain-induced piezoelectric fields

Observation of Ga vacancies in silicon δ-doping superlattices in (001) GaAs

T. Laine, K. Saarinen, J. Mäkinen, P. Hautojärvi, C. Corbel, M. J. Ashwin, and R. C. Newman

Appl. Phys. Lett. 71, 1843 (1997); http://dx.doi.org/10.1063/1.119417 (3 pages) | Cited 5 times

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Positron annihilation experiments have been performed to investigate the compensating defects in silicon δ-doping superlattices in (001) GaAs. The results reveal vacancies and ion-type defects, which are located between the delta planes in undoped GaAs. The vacancy defect is identified as the Ga vacancy and the negative ion is attributed to the Ga antisite. The concentrations of these defects increase strongly, when the areal concentrations of free carriers are reduced at the delta planes. © 1997 American Institute of Physics.
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78.70.Bj Positron annihilation
61.72.J- Point defects and defect clusters
61.80.Fe Electron and positron radiation effects
61.72.S- Impurities in crystals
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Etching and passivation effects on boron-doped amorphous silicon carbide p layer of amorphous silicon solar cell by hydrogen treatment using a mercury-sensitized photochemical vapor deposition method

Jae Hoon Jang and Koeng Su Lim

Appl. Phys. Lett. 71, 1846 (1997); http://dx.doi.org/10.1063/1.119418 (3 pages) | Cited 13 times

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Etching and passivation effects of hydrogen treatment of boron-doped hydrogenated amorphous silicon carbide (a-SiC:H) film used as a p layer of p-i-n type amorphous silicon based solar cells using a mercury-sensitized photochemical vapor deposition method were investigated. For the hydrogen treatment of the p-layer film, longer p-layer deposition time was needed to obtain the same thickness as for no hydrogen treatment because of hydrogen etching effect. However, the cell performance was improved by ∼ 7% due to an increase in the open circuit voltage (Voc) and fill factor (FF) although the p-layer thickness was nearly identical in both cases. The increase in the Voc and FF could be explained by an increase in the built-in potential due to a decrease in the film activation energy. Moreover, the electrical property improvement of the film was well explained by the passivation effect of a SiH2/SiH ratio decrease and a hydrogen content increase calculated from Fourier transformed infrared absorption measurements. © 1997 American Institute of Physics.
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84.60.Jt Photoelectric conversion
81.65.Cf Surface cleaning, etching, patterning
81.65.Rv Passivation
81.05.Gc Amorphous semiconductors
81.05.Cy Elemental semiconductors
78.30.Hv Other nonmetallic inorganics
78.66.Li Other semiconductors
61.43.Dq Amorphous semiconductors, metals, and alloys
78.66.Jg Amorphous semiconductors; glasses

Dynamics of photoexcited holes in n-doped InGaAs/GaAs single quantum well

L. V. Dao, M. Gal, G. Li, and C. Jagadish

Appl. Phys. Lett. 71, 1849 (1997); http://dx.doi.org/10.1063/1.119419 (3 pages) | Cited 6 times

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We have measured the temporal evolution of the photoluminescence (PL) of a Si δ-doped In0.2Ga0.8As/GaAs quantum wells using the PL up-conversion technique. The luminescence spectrum of this sample displayed the characteristic features of the Fermi edge singularity. The temporal evolution of the luminescence is described in terms of the dynamics of the hole population. From the experiments, we have determined the effective hole capture time (15 ps), the interband relaxation time (3 ps), and the radiative decay time (>1 ns) at T = 8 K. We have found that the radiative decay time decreases dramatically with increasing temperature (τr = 45 ps at T = 125 K) which, we believe, is the result of the smearing of the Fermi edge and the delocalization of the holes that are responsible for the luminescence. © 1997 American Institute of Physics.  
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73.61.Ey III-V semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
78.55.Cr III-V semiconductors
78.66.Fd III-V semiconductors
78.47.-p Spectroscopy of solid state dynamics

Direct measurements of electron-longitudinal optical phonon scattering rates in wurtzite GaN

K. T. Tsen, D. K. Ferry, A. Botchkarev, B. Sverdlov, A. Salvador, and H. Morkoç

Appl. Phys. Lett. 71, 1852 (1997); http://dx.doi.org/10.1063/1.119420 (2 pages) | Cited 30 times

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Electron-longitudinal optical phonon scattering rates in wurtzite GaN have been directly measured by subpicosecond time-resolved Raman spectroscopy. We find that the total electron-longitudinal optical phonon scattering rate in GaN is about one order of magnitude larger than that in GaAs. We attribute this enormous increase in the electron-longitudinal optical phonon scattering rate to the much larger ionicity in GaN. © 1997 American Institute of Physics.
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72.80.Ey III-V and II-VI semiconductors
71.20.Nr Semiconductor compounds
71.38.-k Polarons and electron-phonon interactions
78.30.Fs III-V and II-VI semiconductors
63.20.K- Phonon interactions
72.10.Di Scattering by phonons, magnons, and other nonlocalized excitations
78.47.-p Spectroscopy of solid state dynamics

A study on Au/Ni/Au/Ge/Pd ohmic contact and its application to AlGaAs/GaAs heterojunction bipolar transistors

Il-Ho Kim, Sung Ho Park, Tae-Woo Lee, and Moon-Pyung Park

Appl. Phys. Lett. 71, 1854 (1997); http://dx.doi.org/10.1063/1.119421 (3 pages) | Cited 11 times

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An Au/Ni/Au/Ge/Pd ohmic contact system on n-type InGaAs was studied and applied to AlGaAs/GaAs heterojunction bipolar transistors (HBTs). Good ohmic behavior was achieved by rapid thermal annealing (RTA) at temperatures up to 400 °C, and the specific contact resistance was reduced to low-10−6 Ω cm2. However, by annealing at temperatures above 400 °C the characteristics were deteriorated by intermixing and phase reaction of the ohmic metals and InGaAs substrate. The HBTs using the Au/Ni/Au/Ge/Pd ohmic contact scheme showed reliable dc and rf performances with strong dependence on the ohmic contact, especially emitter ohmic contact with RTA temperature. © 1997 American Institute of Physics.
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85.30.Pq Bipolar transistors
73.40.Cg Contact resistance, contact potential
73.40.Ns Metal-nonmetal contacts
61.72.Cc Kinetics of defect formation and annealing
66.30.Ny Chemical interdiffusion; diffusion barriers

Magnetic field-induced noise in directly coupled high Tc superconducting quantum interference device magnetometers

F. P. Milliken, S. L. Brown, and R. H. Koch

Appl. Phys. Lett. 71, 1857 (1997); http://dx.doi.org/10.1063/1.120442 (3 pages) | Cited 24 times

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We have measured the noise of several directly coupled high Tc superconducting quantum interference device (SQUID) magnetometers as we change a static magnetic field B while the devices are superconducting. Devices without “flux dams” show an increase in noise at relatively low magnetic fields B ∼ 1 μT. Devices with flux dams can show no deterioration of the noise characteristics for B as large as 34 μT. The flux dams are part of the pickup loop and limit the circulating current Icirc. If Icirc is kept sufficiently low no vortices are forced into the SQUID loop and the noise performance of the magnetometer remains good. © 1997 American Institute of Physics.
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07.55.Ge Magnetometers for magnetic field measurements
85.25.Dq Superconducting quantum interference devices (SQUIDs)
74.72.-h Cuprate superconductors

A scaling law for ac susceptibility of an YBa2Cu3O film in a perpendicular ac field

G. C. Han, C. K. Ong, S. Y. Xu, and H. P. Li

Appl. Phys. Lett. 71, 1860 (1997); http://dx.doi.org/10.1063/1.119422 (3 pages) | Cited 3 times

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The ac susceptibility (ACS) of an YBa2Cu3O thin film in a perpendicular ac magnetic field (Ha) from 0.22 to 30.8 G is measured as a function of temperature. The temperature dependence of the real (χ′) and imaginary (χ′′) parts of the ACS for various Ha can be well scaled onto a single curve using the peak value (χp″) and temperature (Tp) of χ′′(T) as the scaling parameters. The scaling law suggests that the critical state can be established only below Tp. Above Tp, the ACS is determined by the screening effect of the film due to the sharp decrease of its resistance. Below Tp, the scaling behavior is in agreement with the theoretical approaches based on the critical state model, only if the temperature for zero critical current density is related to the irreversibility temperature Tirr rather than Tc. From the scaling law, we found that Tirr = Tp. © 1997 American Institute of Physics.
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74.78.-w Superconducting films and low-dimensional structures
74.72.-h Cuprate superconductors
74.25.Sv Critical currents

Underdamped long Josephson junction coupled to overdamped single-flux-quantum circuits

Y. M. Zhang, V. Borzenets, V. K. Kaplunenko, and N. B. Dubash

Appl. Phys. Lett. 71, 1863 (1997); http://dx.doi.org/10.1063/1.119423 (3 pages) | Cited 8 times

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We report a circuit that integrates an underdamped long Josephson junction with overdamped single-flux-quantum (SFQ) circuits. We confirm that the resonant soliton modes in the long junction are not affected by SFQ cells coupled to the junction, and demonstrate that the radiation frequency and linewidth of the soliton resonances can be measured with SFQ T-flip-flops. Our experimental results also show that a 4π quantum mechanical phase leap at the end of the long junction, which is due to the reflection of a soliton, creates two single flux quanta propagating in the overdamped Josephson transmission line. © 1997 American Institute of Physics.
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85.25.Cp Josephson devices
85.25.Hv Superconducting logic elements and memory devices; microelectronic circuits
84.30.Sk Pulse and digital circuits

Stable 1 volt programmable voltage standard

S. P. Benz, C. A. Hamilton, C. J. Burroughs, T. E. Harvey, and L. A. Christian

Appl. Phys. Lett. 71, 1866 (1997); http://dx.doi.org/10.1063/1.120189 (3 pages) | Cited 84 times

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Several fully functional programmable voltage standard chips, each having a total of 32 768 Nb–PdAu–Nb Josephson junctions, have been fabricated and tested. The chips are based on a new design that provides fast programmability (1 μs) between voltages and stable voltage operation from −1 to +1 V. A comparison of the new standard with a conventional Josephson voltage standard is in agreement to 0.5±1.1 parts in 109. We demonstrate the utility of this standard by measuring the linearity of a digital voltmeter. © 1997 American Institute of Physics.
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06.20.F- Units and standards
84.37.+q Measurements in electric variables (including voltage, current, resistance, capacitance, inductance, impedance, and admittance, etc.)
85.25.Cp Josephson devices

Structure and uniaxial magnetocrystalline anisotropy of intermetallic compounds La2Co17−xTix

Quanlin Liu, Jingkui Liang, Guanghui Rao, Weihua Tang, Jirong Sun, Xiaolong Chen, and Baogen Shen

Appl. Phys. Lett. 71, 1869 (1997); http://dx.doi.org/10.1063/1.119424 (3 pages) | Cited 5 times

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The crystal structure and magnetic properties of intermetallic compounds La2Co17−xTix (0.8 ⩽ x ⩽ 1.2) have been investigated by x-ray powder diffraction and magnetic measurement. The lattice parameters of La2Co17−xTix with the rhombohedral Th2Zn17-type structure are a = 8.518–8.531 Å, c = 12.344–12.379 Å. Ti atoms show a strong preference for occupying 6c crystallographic positions. The La2Co17−xTix compounds are ferromagnetic. The Curie temperature decreases from 972 to 872 K, and the saturation magnetic moment decreases from 23.2 to 21.3 μB/f.u. with x = 0.8–1.2. The La2Co16Ti compound exhibits favorable uniaxial anisotropy, and the easy magnetization direction is parallel to the c axis. The anisotropy field is 23 kOe at 1.5 K for this compound. © 1997 American Institute of Physics.
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75.30.Gw Magnetic anisotropy
75.50.Cc Other ferromagnetic metals and alloys
61.66.Dk Alloys
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

High spatial resolution quantitative microwave impedance microscopy by a scanning tip microwave near-field microscope

Chen Gao, Tao Wei, Fred Duewer, Yalin Lu, and X.-D. Xiang

Appl. Phys. Lett. 71, 1872 (1997); http://dx.doi.org/10.1063/1.120444 (3 pages) | Cited 84 times

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A recently developed scanning tip microwave near-field microscope has been improved to achieve a spatial resolution of 100 nm ( ∼ λ/106). Furthermore, explicit calculations of the field distribution using a simplified model allow quantitative microscopy of dielectric properties for dielectric materials. A detection sensitivity of δε/ε ∼ 6×10−4 has been achieved. © 1997 American Institute of Physics.
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07.79.Cz Scanning tunneling microscopes

Secondary electron emission from boron-doped diamond under ion impact: Applications in single-ion detection

Tomihiro Kamiya, Marian Cholewa, Andrew Saint, Steven Prawer, George J. F. Legge, James E. Butler, and Daniel J. Vestyck

Appl. Phys. Lett. 71, 1875 (1997); http://dx.doi.org/10.1063/1.120190 (3 pages) | Cited 7 times

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The secondary electron emission from a 2 μm thick boron-doped diamond film under ion (4.6–7.7 MeV He+)impact is reported. The yield under ions impact is found to be remarkably high, stable over a period of many months, and independent of which side of the film (i.e., growth or substrate side) is exposed to the ion flux. By taking advantage of the high secondary-electron yield, the passage of each ion through the film could be detected with an efficiency of close to 100%, which to the best of our knowledge is the highest efficiency recorded to date for any thin-film window. This finding has an immediate application in single-ion irradiation systems where a thin vacuum window is required to allow extraction of an ion beam from the vacuum into air and at the same time offer 100% efficiency for the detection of the passage of the ion through the window. © 1997 American Institute of Physics.
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81.05.ub Fullerenes and related materials
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
79.20.Hx Electron impact: secondary emission

Electrostatic force microscopy of silver nanocrystals with nanometer-scale resolution

Ralph M. Nyffenegger, Reginald M. Penner, and Rainer Schierle

Appl. Phys. Lett. 71, 1878 (1997); http://dx.doi.org/10.1063/1.119425 (3 pages) | Cited 26 times

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Silver nanoparticles on graphite basal plane surfaces were concurrently imaged using electrostatic force microscopy (EFM) and noncontact atomic force microscopy. EFM images were obtained having a lateral resolution of 4–5 nm, and a resolution perpendicular to the surface of ≈ 1 nm. The dependence of the contrast in the EFM data for the silver nanoparticles as a function of the applied tip bias was consistent with a positive charge for the silver nanocrystals on the graphite surface, qualitatively as expected by theory. © 1997 American Institute of Physics.
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68.55.-a Thin film structure and morphology
61.46.-w Structure of nanoscale materials
68.35.B- Structure of clean surfaces (and surface reconstruction)

Nanoscale silicon field effect transistors fabricated using imprint lithography

Lingjie Guo, Peter R. Krauss, and Stephen Y. Chou

Appl. Phys. Lett. 71, 1881 (1997); http://dx.doi.org/10.1063/1.119426 (3 pages) | Cited 50 times

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We report the fabrication and characterization of nanoscale silicon field effect transistors using nanoimprint lithography. With this lithographic technique and dry etching, we have patterned a variety of nanoscale transistor features in silicon, including 100 nm wire channels, 250-nm-diam quantum dots, and ring structures with 100 nm ring width, over a 2×2 cm lithography field with good uniformity. Compared with devices fabricated by the conventional electron-beam lithography, we did not observe any degradation in the device characteristics. The successful fabrication of the semiconductor nanodevices represents a step forward to make nanoimprint lithography a viable technique for the mass production of semiconductor devices. © 1997 American Institute of Physics.  
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85.40.Hp Lithography, masks and pattern transfer
85.30.Tv Field effect devices
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
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)

Microprobe x-ray fluorescence with the use of point-focusing diffractors

Z. W. Chen and D. B. Wittry

Appl. Phys. Lett. 71, 1884 (1997); http://dx.doi.org/10.1063/1.119427 (3 pages) | Cited 9 times

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A toroidal point-focusing mica crystal diffractor was used to focus monochromatic x rays from a microfocus x-ray source operated at 0.1 mA and 30 kV. The Cu Kα x-ray focal spot of 50 μm×85 μm had 1.6×104 photons/s/μm2. Microprobe x-ray fluorescence (MXRF) spectra were recorded with a Si(Li) energy dispersive detector for bulk specimens of GaAs, Si, and Muscovite. Low background due to monochromatic excitation resulted in predicted detection limits as low as 2 ppm for a measurement time of 500 s. Laboratory MXRF systems based on point-focusing diffractors were shown to provide lower detection limits, larger working distance, and higher theoretical intensity than systems using capillary optics. © 1997 American Institute of Physics.
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82.80.Ej X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods
FREE

Due to an error in printing, the following article, originally published in the 4 August 1997 issue, is being republished in its entirety. Morphology definition by disclinations and dislocations in a mesostructured silicate crystal

J. Feng, Q. Huo, P. M. Petroff, and G. D. Stucky

Appl. Phys. Lett. 71, 1887 (1997); http://dx.doi.org/10.1063/1.120198 (3 pages) | Cited 5 times

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Curved surface morphologies resulting from disclinations are unusual in inorganic phases because the relatively large lattice energies generally permit only translational dislocations. In this letter, we show, however, that disclinations can be readily observed and identified in composite organic/inorganic phases. Disclinations and dislocations in MCM-41, a two-dimensional hexagonal (p6mm) mesophase crystal synthesized using silicate and surfactant precursors, were investigated by using transmission electron microscopy. We observed two types of dislocations and two types of disclinations. All dislocations observed are of the smallest Burgers vector a (the basis vector). Dislocation dipoles and disclination quadrupoles appear more frequently than isolated ones. © 1997 American Institute of Physics.
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61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)
FREE

Due to an error in printing, the following article, originally published in the 4 August 1997 issue, is being republished in its entirety. Demonstration of an imide coupling reaction on a Si(100)-2×1 surface by molecular layer deposition

T. Bitzer and N. V. Richardson

Appl. Phys. Lett. 71, 1890 (1997); http://dx.doi.org/10.1063/1.120199 (3 pages) | Cited 1 time

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In this letter, we report the successful growth of an ultrathin organic film on Si(100)-2×1 by reactive coupling of polyimide precursors. Using the molecular layer deposition technique, 1,4-phenylene diamine and pyromellitic dianhydride were sequentially dosed on clean Si(100)-2×1 under ultrahigh vacuum conditions. The interfacial imidization was initiated by thermal curing at 200 °C. High resolution electron energy loss spectroscopy was employed to identify surface species. The spectra show clearly, that an oligimide chain has been formed which stands upright on the substrate. The chain bonds to the silicon substrate via a Si–(NH)–C linkage. © 1997 American Institute of Physics.
Show PACS
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.65.-b Surface treatments
73.61.Ng Insulators
68.35.Ct Interface structure and roughness
68.55.-a Thin film structure and morphology
79.20.Kz Other electron-impact emission phenomena
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
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