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1 Mar 2005

Volume 97, Issue 5, Articles (05xxxx)

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Spectroscopic ellipsometric study on dispersion of optical constants of Gd2O3 films

D. Bhattacharyya and A. Biswas

J. Appl. Phys. 97, 053501 (2005); http://dx.doi.org/10.1063/1.1852693 (7 pages) | Cited 9 times

Online Publication Date: 8 February 2005

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Electron-beam evaporated Gd2O3 films have been characterized by spectroscopic ellipsometry technique. The experimental ellipsometric data have been fitted with theoretical models to derive information on the sample structure and dispersion of the optical constants of bulk Gd2O3. Three different dispersion models, proposed so far for amorphous materials have been used for the calculation of the refractive-index dispersion and results obtained from these models have been compared.
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68.55.-a Thin film structure and morphology
78.66.Nk Insulators
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Electrical resistance of low-angle tilt grain boundaries in acceptor-doped SrTiO3 as a function of misorientation angle

Roger A. De Souza, Jürgen Fleig, Joachim Maier, Zaoli Zhang, Wilfried Sigle, and Manfred Rühle

J. Appl. Phys. 97, 053502 (2005); http://dx.doi.org/10.1063/1.1853495 (7 pages) | Cited 22 times

Online Publication Date: 8 February 2005

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The transport of charge across symmetrical low-angle [001] tilt grain boundaries in Fe-doped SrTiO3 was examined. Grain boundary resistances were obtained from impedance spectroscopy measurements on bicrystals with misorientation angles θ = 2.3°, 5.4°, and 7.8° as a function of temperature and oxygen partial pressure. By comparing these data with values predicted from a double Schottky-barrier model, we show that the resistance of a low-angle tilt grain boundary in acceptor-doped SrTiO3 is correlated with its dislocation content, but in a nontrivial manner.
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61.72.Mm Grain and twin boundaries
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
72.80.Sk Insulators
72.20.Fr Low-field transport and mobility; piezoresistance
68.35.Ct Interface structure and roughness
68.35.Dv Composition, segregation; defects and impurities
82.80.Fk Electrochemical methods
77.22.Jp Dielectric breakdown and space-charge effects
68.37.Lp Transmission electron microscopy (TEM)

The effect of antimony in the growth of indium arsenide quantum dots in gallium arsenide (001)

Y. Sun, S. F. Cheng, G. Chen, R. F. Hicks, J. G. Cederberg, and R. M. Biefeld

J. Appl. Phys. 97, 053503 (2005); http://dx.doi.org/10.1063/1.1858054 (6 pages) | Cited 12 times

Online Publication Date: 8 February 2005

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The effect of an initial saturation coverage of antimony on the growth of indium arsenide quantum dots on gallium arsenide has been studied during metalorganic vapor-phase epitaxy. After depositing one to two bilayers of InAs at 723 K, the samples were quenched, transferred to ultrahigh vacuum, and characterized by scanning tunneling microscopy and x-ray photoelectron spectroscopy. It has been found that the critical thickness for onset of quantum dot formation is 33% less with Sb present as compared to without Sb. The antimony incorporates into the quantum dots, increasing their density and total volume, and causing them to be more densely clustered together.
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81.07.Ta Quantum dots
81.05.Ea III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.65.Hb Quantum dots (patterned in quantum wells)
81.15.Kk Vapor phase epitaxy; growth from vapor phase
61.72.uj III-V and II-VI semiconductors
61.72.S- Impurities in crystals
81.40.Gh Other heat and thermomechanical treatments
68.55.-a Thin film structure and morphology
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
79.60.Bm Clean metal, semiconductor, and insulator surfaces
79.60.Jv Interfaces; heterostructures; nanostructures
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Xy Scanning Auger microscopy, photoelectron microscopy

Transmission electron microscopy study on Nd-rich phase and grain boundary structure of Nd–Fe–B sintered magnets

Y. Shinba, T. J. Konno, K. Ishikawa, K. Hiraga, and M. Sagawa

J. Appl. Phys. 97, 053504 (2005); http://dx.doi.org/10.1063/1.1851017 (8 pages) | Cited 41 times

Online Publication Date: 9 February 2005

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The crystal structure and morphology of the Nd-rich phase in postannealed sintered Nd–Fe–B hard magnets were investigated by transmission electron microscopy (TEM). The Nd-rich phase at grain boundaries thinner than about 2 nm was found to be amorphous; as the boundary region broadened, it assumed a face-centered cubic (fcc) structure with a ≈ 0.54 nm; eventually, the selected area diffraction pattern exhibited systematically allowed superlattice spots, revealing that the Nd-rich phase belongs to the space group Iamath with a ≈ 1.1 nm. The elemental analysis of the Nd-rich phase showed that it contains a considerable amount of oxygen. These findings indicate that the Nd-rich phase with a ≈ 1.1 nm is in fact isostructural to cubic Nd2O3 (Mn2O3 structure). We also found Nd-rich fcc precipitates (a ≈ 0.54 nm) of several ten to hundred nm inside the Nd2Fe14B grains. Both intergranular and intragrain Nd-rich phases possess simple orientation relationships with the matrix Nd2Fe14B phase, such as (111)Nd2Fe14B‖(111)Nd‐rich [math11]Nd2Fe14B‖[math11]Nd‐rich and (010)Nd2Fe14B‖(111)Nd‐rich [001]Nd2Fe14B‖[math10]Nd‐rich. Our Lorentz TEM observation suggested that the intragrain Nd-rich precipitates frequently disrupt magnetic domain wall arrangements, and that the magnetic interactions across thin amorphous Nd-rich phase are dominated by a simple dipole interaction.
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75.50.Ww Permanent magnets
75.50.Vv High coercivity materials
61.66.Dk Alloys
61.72.Mm Grain and twin boundaries
75.60.Ch Domain walls and domain structure
75.30.Cr Saturation moments and magnetic susceptibilities
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Et Exchange and superexchange interactions
81.40.Gh Other heat and thermomechanical treatments
79.20.Kz Other electron-impact emission phenomena
68.37.Lp Transmission electron microscopy (TEM)

Structural, optical, and electrical properties of AgIn5Te8

A. Sánchez, L. Meléndez, J. Castro, J. A. Hernández, E. Hernández, and C. A. Durante Rincón

J. Appl. Phys. 97, 053505 (2005); http://dx.doi.org/10.1063/1.1854207 (4 pages) | Cited 3 times

Online Publication Date: 9 February 2005

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AgIn5Te8 was prepared by direct fusion of the stoichiometric mixture of the elements in an evacuated quartz ampoule. The analysis of x-ray powder diffraction data showed the presence of one single phase with tetragonal structure. The lattice parameters a = 6.212 Å and c = 12.456 Å were refined by means of the program WINPLOTR. Congruent fusion at 698 °C was observed by differential thermal analysis measurements performed on samples sealed in evacuated quartz ampoules. Transmittance measurements were used to determine the absorption coefficient α. Two absorption edges were observed, one indirect at 1.1 eV and one direct at 1.28 eV, obtained from a plot of (α×hν)1/2 vs hν and (α×hν)2 vs hν, respectively. A six-probe configuration was used to measure the electrical resistivity and the Hall coefficient from 10 to 400 K. The activation energies values, estimated at 1.1 and 1.27 eV from Arrhenius plots of the resistivity and the Hall coefficient, respectively, agree with those obtained for the energy gaps by optical measurements.
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78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
72.80.Jc Other crystalline inorganic semiconductors
61.66.Fn Inorganic compounds
72.20.My Galvanomagnetic and other magnetotransport effects
81.70.Pg Thermal analysis, differential thermal analysis (DTA), differential thermogravimetric analysis

Surface tension and viscosity of liquid and undercooled tantalum measured by a containerless method

Paul-François Paradis, Takehiko Ishikawa, and Shinichi Yoda

J. Appl. Phys. 97, 053506 (2005); http://dx.doi.org/10.1063/1.1854211 (3 pages) | Cited 5 times

Online Publication Date: 10 February 2005

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Electrostatic levitation and multibeam radiative heating overcame contamination and sample position stability problems associated with handling of liquid tantalum. This approach allowed the measurements of the surface tension and the viscosity of the superheated and undercooled states of tantalum using the oscillation drop method. The measurements of the surface tension could be expressed as σ(T) = 2.15×103−0.21(T−Tm) mN m−1 over the 2970–3400 K interval, where Tm is the melting temperature (3290 K). The value at Tm agrees well with the scarce data appearing in the literature. Similarly, on the 3000–3400 K temperature range, the viscosity was determined as η(T) = 0.0035 exp[213.3/(RT)](mPa s).
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68.03.Cd Surface tension and related phenomena
66.20.-d Viscosity of liquids; diffusive momentum transport

Efficient excitation of cavity resonances of subwavelength metallic gratings

P. Quémerais, A. Barbara, J. Le Perchec, and T. López-Ríos

J. Appl. Phys. 97, 053507 (2005); http://dx.doi.org/10.1063/1.1854727 (4 pages) | Cited 8 times

Online Publication Date: 10 February 2005

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One-dimensional rectangular metallic gratings enable enhanced transmission of light for specific resonance frequencies. Two kinds of modes participating in enhanced transmission have already been demonstrated: waveguide modes and surface plasmon polaritons. Since the original article by Hessel and Oliner [Appl. Opt. 4, 1275 (1965) ] pointing out the existence of waveguide modes, little progress was made in their understanding. We present here a careful analysis, and show that the coupling between the light and such resonances can be tremendously improved using an evanescent wave. This leads to enhanced localization of light in cavities, yielding, in particular, a very selective light transmission through these gratings.
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42.79.Dj Gratings
42.79.Gn Optical waveguides and couplers
42.79.Bh Lenses, prisms and mirrors

Polarization holograms in azo dye-doped polymer dissolved liquid crystal composites

Hiroshi Ono, Fumihiro Takahashi, Akira Emoto, and Nobuhiro Kawatsuki

J. Appl. Phys. 97, 053508 (2005); http://dx.doi.org/10.1063/1.1858063 (8 pages) | Cited 19 times

Online Publication Date: 10 February 2005

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We have investigated holographic recordings in azobenzene-containing amorphous polymers (AP) and polymer-dissolved liquid-crystalline composites (PDLCC) with two waves that have orthogonal linear polarizations. Only linear photobirefringence was induced in AP, while both linear and circular photobirefringences were induced in PDLCC. The value of the photoinduced linear and circular birefringences had an effect on the diffraction properties in the polarization holographic gratings. The diffraction properties in AP and PDLCC samples were well explained by theoretical calculation on the basis of the Jones analysis.
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42.40.Eq Holographic optical elements; holographic gratings
42.70.Ln Holographic recording materials; optical storage media
42.40.Ht Hologram recording and readout methods
42.70.Jk Polymers and organics
42.70.Df Liquid crystals
78.20.Fm Birefringence

Self-organized growth of tetrathiafulvalene–tetracyanoquinodimethane molecular wires using the coevaporation method under a static electric field

Masatoshi Sakai, Masaaki Iizuka, Masakazu Nakamura, and Kazuhiro Kudo

J. Appl. Phys. 97, 053509 (2005); http://dx.doi.org/10.1063/1.1852698 (4 pages) | Cited 9 times

Online Publication Date: 11 February 2005

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Wire-like crystals of tetrathiafulvalene-tetracyanoquinodimethane (TTF–TCNQ) charge-transfer complexes were grown under a static electric field by employing electric-field assisted evaporation. TTF–TCNQ molecular wires grew from the edges of two gold electrodes opposite to each other along the electric lines of force, and finally make a connection at their front end to form a single wire. Self-organization of the wire bridge is derived from a higher local electric field between the tips of the opposing molecular wires. Oriented molecular wires, which have diffuse branches, exhibit the effects of a local electric field. Preferential growth of TCNQ at the tip of the molecular wire during coevaporation of TTF and TCNQ is clearly revealed by microscopic Raman spectroscopy. Asymmetrical growth of coevaporated TTF–TCNQ wire under a static electric field is dominated by the drift motion of TCNQ−.
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81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
81.07.Nb Molecular nanostructures
81.16.Dn Self-assembly
61.46.-w Structure of nanoscale materials
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
78.67.Bf Nanocrystals, nanoparticles, and nanoclusters
78.30.Jw Organic compounds, polymers
82.30.Fi Ion-molecule, ion-ion, and charge-transfer reactions

Growth mechanism of InAs quantum dots on GaAs by metal-organic chemical-vapor deposition

Theodore Chung, Gabriel Walter, and Nick Holonyak

J. Appl. Phys. 97, 053510 (2005); http://dx.doi.org/10.1063/1.1856218 (4 pages) | Cited 7 times

Online Publication Date: 11 February 2005

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The growth parameters affecting the deposition of InAs quantum dots (QDs) by metal-organic chemical-vapor deposition are reported. Experiments with arsine pause, gas switching, and hydrogen shroud flow show that a low V∕III ratio is the key to obtaining three-dimensional InAs island formation with high density and uniformity. Based on atomic force microscopy images of InAs QDs deposited under different growth conditions, a physical model for the epitaxial growth of three-dimensional islands is proposed. In this model, the InAs QD growth is governed by two types of arsenic sources at the growth surface: free arsenic atoms arriving at the boundary layer and dangling arsenic bonds available at the GaAs wafer surface. At high V∕III ratio, free arsenic atoms arriving at the boundary layer are the dominant hydride species and produce a low density of InAs islands with irregular shape and polycrystalline defects. At low V∕III ratio arsenic bonds on the GaAs surface are the main sites for indium atoms to attach to, thus producing high island densities and small coherent island sizes.
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81.07.Ta Quantum dots
81.05.Ea III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.65.Hb Quantum dots (patterned in quantum wells)
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.37.Ps Atomic force microscopy (AFM)

High-resolution transmission electron microscopy study of the interfaces and stacking defects in superconducting/magnetic perovskite superlattices

N. Haberkorn, F. Lovey, A. M. Condó, and J. Guimpel

J. Appl. Phys. 97, 053511 (2005); http://dx.doi.org/10.1063/1.1858059 (7 pages) | Cited 10 times

Online Publication Date: 11 February 2005

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We studied the microstructure of GdBa2Cu3O7−δ/La0.6Sr0.4MnO3 superlattices grown on (001)MgO substrates by high-resolution transmission electron microscopy. The superlattices show two different epitaxial growths. In addition different types of interfaces between the layers were found. Moreover, several kinds of stacking faults and domain boundaries were observed in both materials. The crystallography of the interfaces and the defects was analyzed and their role on the physical properties of the superlattices is discussed.
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74.72.-h Cuprate superconductors
75.50.Dd Nonmetallic ferromagnetic materials
74.78.-w Superconducting films and low-dimensional structures
68.65.Cd Superlattices
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
68.35.Ct Interface structure and roughness
61.72.Nn Stacking faults and other planar or extended defects
68.37.Lp Transmission electron microscopy (TEM)
61.72.Mm Grain and twin boundaries

Measurement of second order susceptibilities of GaN and AlGaN

N. A. Sanford, A. V. Davydov, D. V. Tsvetkov, A. V. Dmitriev, S. Keller, U. K. Mishra, S. P. DenBaars, S. S. Park, J. Y. Han, and R. J. Molnar

J. Appl. Phys. 97, 053512 (2005); http://dx.doi.org/10.1063/1.1852695 (13 pages) | Cited 17 times

Online Publication Date: 14 February 2005

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Rotational Maker fringes, scaled with respect to χ11(2) of crystalline quartz, were used to determine the second order susceptibilities χ31(2) and χ33(2) for samples of thin AlxGa1−xN films, a thicker GaN film, and a free-standing GaN platelets. The pump wavelength was 1064 nm. The AlxGa1−xN samples, ranging in thickness from roughly 0.5 to 4.4 μm, were grown by metalorganic chemical vapor deposition (MOCVD) and hydride vapor-phase epitaxy (HVPE) on (0001) sapphire substrates. The Al mole fractions x were 0, 0.419, 0.507, 0.618, 0.660, and 0.666, for the MOCVD-grown samples, and x = 0, 0.279, 0.363, and 0.593 for the HVPE-grown samples. An additional HVPE-grown GaN sample ∼ 70 μm thick was also examined. The free-standing bulk GaN platelets consisted of an HVPE grown film ∼ 226 μm thick removed from its growth substrate, and a crystal ∼ 160 μm thick grown by high-pressure techniques. For the AlxGa1−xN samples, the magnitudes of χ31(2) and χ33(2) decrease roughly linearly with increasing x and extrapolate to ∼ 0 for x = 1. Furthermore, the constraint expected for a perfect wurtzite structure, namely χ33(2) = −2χ31(2), was seldom observed, and the samples with x = 0.660 and x = 0.666 showed χ31(2) and χ33(2) having the same sign. These results are consistent with the theoretical studies of nonlinear susceptibilities for AlN and GaN performed by Chen et al. [Appl. Phys. Lett. 66, 1129 (1995)] . The thicker bulk GaN samples displayed a complex superposition of high- and low-frequency Maker fringes due to the multiple-pass interference of the pump and second-harmonic generation beams, and the nonlinear coefficients were approximately consistent with those measured for the thin-film GaN sample.
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78.66.Fd III-V semiconductors
42.65.An Optical susceptibility, hyperpolarizability
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
68.55.-a Thin film structure and morphology
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
68.55.Nq Composition and phase identification

Isothermal equations of state of beta octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine at high temperatures

Jared C. Gump and Suhithi M. Peiris

J. Appl. Phys. 97, 053513 (2005); http://dx.doi.org/10.1063/1.1856227 (7 pages) | Cited 13 times

Online Publication Date: 14 February 2005

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Isothermal pressure-volume equations of state of beta HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) at temperatures of 30, 100, and 140 °C under both hydrostatic and nonhydrostatic compressions have been obtained using synchrotron angle-dispersive x-ray diffraction experiments. The samples were heated to the isotherm temperature and compressed up to 5.8 GPa. At all temperatures HMX remained in the beta phase up to 5.8 GPa. However, at 140 °C upon decompression to ambient from nonhydrostatic pressures above 4 GPa, HMX underwent a phase transition to the delta phase. The same transition was seen upon decompression to ambient from hydrostatic compression; however, parts of the sample remain in the β phase, resulting in a mixed-phase sample. The diffraction data were analyzed to yield unit-cell dimensions at each pressure, and further analyzed to yield thermal expansion, bulk modulus, and the pressure derivative of the bulk modulus.
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64.30.-t Equations of state of specific substances
62.50.-p High-pressure effects in solids and liquids
65.40.De Thermal expansion; thermomechanical effects
64.70.K- Solid-solid transitions
81.40.Vw Pressure treatment
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.D- Elasticity

First-principles investigations of nitrogen-doping effects on defect aggregation processes in Czochralski Si

A. Taguchi, H. Kageshima, and K. Wada

J. Appl. Phys. 97, 053514 (2005); http://dx.doi.org/10.1063/1.1858057 (5 pages) | Cited 6 times

Online Publication Date: 14 February 2005

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We theoretically investigated the nitrogen (N)-doping effect on vacancy aggregation and oxygen precipitation processes in Czochralski Si. By using first-principles calculations, we investigated stable atomic configurations and formation energies of various complexes formed by vacancies (V), oxygen (O), and N. It was found that V and O form stable complexes, but some O capture processes are endothermic, suggesting that the V aggregation preferentially occurs, resulting in void growth. It was also found that the {N2–V2} complex, which is already known as the most stable complex among N and V complexes, effectively captures several O atoms, and then forms stable {N2–V2–On} complexes. The stable {N2–V2–On} complexes may become the heterogeneous nucleation sites of the O precipitates, suggesting that the N doping drives the aggregation of O. This is consistent with the experimentally observed enhancement of O precipitate formation due to N doping. The experimentally observed shape change of the void may be due to anisotropic void growth originating from the N and N–O involved in void formation during the growth.
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61.72.uf Ge and Si
61.72.J- Point defects and defect clusters
71.15.Pd Molecular dynamics calculations (Car-Parrinello) and other numerical simulations
71.20.Mq Elemental semiconductors
61.72.Qq Microscopic defects (voids, inclusions, etc.)
64.75.-g Phase equilibria

Photoreflectance and photoluminescence investigations of a step-like GaInNAsSb/GaAsN/GaAs quantum well tailored at 1.5 μm: The energy level structure and the Stokes shift

R. Kudrawiec, H. B. Yuen, K. Ryczko, J. Misiewicz, S. R. Bank, M. A. Wistey, H. P. Bae, and James S. Harris

J. Appl. Phys. 97, 053515 (2005); http://dx.doi.org/10.1063/1.1854729 (7 pages) | Cited 9 times

Online Publication Date: 15 February 2005

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The energy level structure of a step-like GaInNAsSb/GaNAs/GaAs quantum well (QW) has been investigated by photoreflectance (PR) spectroscopy and was analyzed by theoretical calculations. In the active region of this structure, i.e., GaInNAsSb/GaNAs QW, we have observed PR resonances related higher order QW transitions in addition to the ground state transition. Based on calculations from experimental data, we have found that the electron effective mass in the active QW is 0.12m0 and the conduction band offset for GaInNAsSb/GaAs interface is about 0.85. The emission observed from this structure at 10 K has a small Stokes shift (i.e., 6 meV and <2 meV for as-grown and annealed structures, respectively) and is without the exponential-like tail at the low-energy side. Hence, we conclude that the incorporation of Sb atoms into GaInNAs alloy helps to achieve QW structures which emit light at longer wavelength and have quite narrow emission line and small Stokes shift.
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78.67.De Quantum wells
73.21.Fg Quantum wells
73.20.At Surface states, band structure, electron density of states
78.55.Cr III-V semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
61.72.Cc Kinetics of defect formation and annealing

Silent Raman modes in zinc oxide and related nitrides

F. J. Manjón, B. Marí, J. Serrano, and A. H. Romero

J. Appl. Phys. 97, 053516 (2005); http://dx.doi.org/10.1063/1.1856222 (4 pages) | Cited 86 times

Online Publication Date: 16 February 2005

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Anomalous Raman modes have been reported in several recent papers dealing with doped- and undoped-ZnO layers grown by different methods. Most of these anomalous Raman modes have been attributed to local vibrational modes of impurities or defects. However, we will show that most of the observed modes correspond to wurtzite-ZnO silent modes allowed by the breakdown of the translational crystal symmetry induced by defects and impurities.
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63.20.Pw Localized modes
78.66.Hf II-VI semiconductors
78.55.Et II-VI semiconductors
78.30.Fs III-V and II-VI semiconductors

Surface microroughness of ion-beam etched optical surfaces

N. Savvides

J. Appl. Phys. 97, 053517 (2005); http://dx.doi.org/10.1063/1.1856228 (7 pages) | Cited 4 times

Online Publication Date: 16 February 2005

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Ion-beam etching (IBE) and ion-beam figuring techniques using low-energy ion-beam sources have been applied for more than ten years in the fabrication and finishing of extremely smooth high-performance optics. We used optical interferometric techniques and atomic force microscopy to study the evolution of the surface root-mean-square (rms) microroughness, Rq, as a function of depth of a material removed (0–3000 nm) by a broad ion-beam source (Ar+ ions of energy 600 eV and ion current density of 1 mA cm−2). Highly polished samples of fused silica and Zerodur (Rq ∼ 3.5 Å) showed a small decrease in microroughness (to 2.5 Å) after 3000-nm IBE removal while an ultrapolished single-crystal sapphire sample (Rq ∼ 1 Å rms) retained its very low microroughness during IBE. Power spectral density functions over the spatial frequency interval of measurement (f = 5×10−3−25 μm−1) indicate that the IBE surfaces have minimal subsurface damage and low optical scatter.
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81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
68.35.B- Structure of clean surfaces (and surface reconstruction)
81.65.Cf Surface cleaning, etching, patterning
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
68.37.Ps Atomic force microscopy (AFM)
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