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18 Jan 1988

Volume 52, Issue 3, pp. 173-246


Undulator generating any kind of elliptically polarized radiation

Hideo Onuki, Norio Saito, and Terubumi Saito

Appl. Phys. Lett. 52, 173 (1988); http://dx.doi.org/10.1063/1.99510 (3 pages) | Cited 25 times

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A new type of undulator with crossed and retarded magnetic fields which enables us to obtain any kind of elliptically polarized synchrotron radiation from relativistic electrons was developed. This undulator was installed in a straight section of the electron storage ring, TERAS, and its polarization characteristics were investigated. The experimental results proved that this device can generate linearly or circularly polarized synchrotron radiation which would be very useful in polarization modulation spectroscopy.
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07.85.-m X- and γ-ray instruments

Mapping of microelectric and magnetic fields with double‐exposure electron holography

G. Matteucci, G. F. Missiroli, J. W. Chen, and G. Pozzi

Appl. Phys. Lett. 52, 176 (1988); http://dx.doi.org/10.1063/1.99511 (3 pages) | Cited 15 times

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The double‐exposure electron holographic technique has been put into practical use for the first time. By this method an accurate recording of the distribution of electric and magnetic fields can be directly obtained by the electron microscope without resorting to sophisticated optical manipulation of the holograms. Problems concerning the operative definition of the contour maps are discussed. Experimental results are presented.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers
75.70.Kw Domain structure (including magnetic bubbles and vortices)
41.75.Fr Electron and positron beams

Degradation phenomenology in (Al)GaAs quantum well lasers

R. G. Waters and R. K. Bertaska

Appl. Phys. Lett. 52, 179 (1988); http://dx.doi.org/10.1063/1.99512 (3 pages) | Cited 10 times

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The degradation rates for continuously operated quantum well lasers with natural facets have been investigated. For most devices, a simple functional relationship exists between degradation rate and operating current density and the data suggest that the role of optical flux is secondary. For device configurations with high excess nonradiative current densities, however, exceptionally high degradation rates are observed and a correlation is proposed.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.55.Px Semiconductor lasers; laser diodes

Room‐temperature excitonic optical nonlinearities of molecular beam epitaxially grown ZnSe thin films

N. Peyghambarian, S. H. Park, S. W. Koch, A. Jeffery, J. E. Potts, and H. Cheng

Appl. Phys. Lett. 52, 182 (1988); http://dx.doi.org/10.1063/1.99513 (3 pages) | Cited 31 times

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Large optical nonlinearities have been observed in molecular beam epitaxially grown thin films of ZnSe at room temperature and at T=150 K. A comparison with a plasma theory indicates that in both cases exciton screening is the dominating mechanism for the nonlinearity. The maximum nonlinear index per excited electron‐hole pair at room temperature is comparable to that of bulk GaAs and GaAs‐AlGaAs multiple quantum wells. The measured absorption and nonlinear index spectra agree quite well with our calculated values.
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78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Similarities between the initial phase of a transient nonuniform glow discharge in nitrogen and the negative corona Trichel pulse formation in an electronegative gas

Mirko Černák and Tatsuzo Hosokawa

Appl. Phys. Lett. 52, 185 (1988); http://dx.doi.org/10.1063/1.99514 (3 pages) | Cited 7 times

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Measurements have been made of the initial stage of breakdown in a short negative point‐to‐plane gap in nitrogen at pressures of 50–750 Torr and at various overvoltages. The transient glow discharge regime was found to be preceded by a peaked current signal of conspicuous similarity to the Trichel pulse rise and its initial decay in an electronegative gas.
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52.80.Hc Glow; corona

Direct force measurement in scanning tunneling microscopy

S. L. Tang, J. Bokor, and R. H. Storz

Appl. Phys. Lett. 52, 188 (1988); http://dx.doi.org/10.1063/1.99515 (3 pages) | Cited 22 times

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A novel force measurement using a scanning tunneling microscope as a forced oscillator is described. Results obtained from tunneling between a tungsten tip and a graphite substrate show that a maximum tip‐sample force about 10−6 N exists during the constant current mode of operation. These results are in agreement with a previous model where large contact areas insulated by contaminants between tip and substrate were suggested as a cause of large tip‐sample interaction forces. This method can achieve a force sensitivity of 10−8 N and for conductive substrates provide a simple, versatile alternative to existing methods of atomic force microscopy.
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07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination
07.78.+s Electron, positron, and ion microscopes; electron diffractometers
68.35.B- Structure of clean surfaces (and surface reconstruction)

Unusual room‐temperature intermixing and oxidation in copper deposited on a fluorinated amorphous silicon system

C. Cytermann, R. Brener, E. Sacher, B. Pratt, and R. Weil

Appl. Phys. Lett. 52, 191 (1988); http://dx.doi.org/10.1063/1.99516 (3 pages) | Cited 12 times

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The room‐temperature behavior of Cu thin films on crystalline and amorphous silicon (c‐Si and a‐Si) substrates was studied by Auger electron spectroscopy. All samples, except Cu/ a‐Si:F, behaved as usual metal on silicon systems. It was found that F greatly enhances Cu‐Si intermixing which proceeds up to the sample surface. After prolonged room‐temperature exposure to air, this system settles into the unusual configuration: Cu/SiO2/a‐Si:F. The effect is explained in terms of the permeability of Cu3Si to oxygen and the low solubility of Cu in SiO2.
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68.35.Fx Diffusion; interface formation
81.65.-b Surface treatments
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Study of electromigration‐induced resistance and resistance decay in Al thin‐film conductors

J. R. Lloyd and R. H. Koch

Appl. Phys. Lett. 52, 194 (1988); http://dx.doi.org/10.1063/1.99517 (3 pages) | Cited 21 times

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Using an ac Bridge technique, the resistance of thin‐film (500 nm thick) Al and AlCu(5%) conductor stripes was monitored during high direct current density (1×106 A cm−2) stressing. The resistance was found to increase approximately linearly with time during stressing with a rate that was thermally activated. Surprisingly the activation energy varied considerably between nominally identical samples. After 3 h of stressing, the current was turned off and an exponential decay in the resistance was observed with a time constant of several hours. The decay was also thermally activated with an energy that varied from film to film. Both results suggest that the activation energy for resistance change during electrical stress can be significantly different in nominally identical films.
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73.61.At Metal and metallic alloys
66.30.Qa Electromigration
81.40.Rs Electrical and magnetic properties related to treatment conditions

Stability and epitaxy of NiAl and related intermetallic films on III‐V compound semiconductors

T. Sands

Appl. Phys. Lett. 52, 197 (1988); http://dx.doi.org/10.1063/1.99518 (3 pages) | Cited 56 times

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The cubic transition metal‐gallium and transition metal‐aluminum intermetallic compounds with the CsCl structure (e.g., NiGa and CoAl) have been identified as candidate materials for stable and epitaxical contacts to III‐V semiconductors. Fabrication of these stable and epitaxical contacts using only conventional vacuum deposition (e.g., electron gun evaporation) has been demonstrated for the NiAl/GaAs system. It is expected that this unique class of contact materials will find application in III‐V‐based field‐effect transistors as well as novel electronic and photonic devices based on multiple semiconductor/metal heterojunctions.
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81.15.Kk Vapor phase epitaxy; growth from vapor phase
73.40.Ns Metal-nonmetal contacts
68.60.Dv Thermal stability; thermal effects
85.30.Tv Field effect devices

Specific lattice location of Zn in CdTe determined by ion‐channeling methods

T. Haga, H. Suzuki, M. H. Rashid, Y. Abe, and A. Tanaka

Appl. Phys. Lett. 52, 200 (1988); http://dx.doi.org/10.1063/1.99653 (3 pages) | Cited 4 times

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The specific lattice location of Zn in CdTe single crystals has been investigated by ion‐channeling methods combined with particle‐induced x‐ray emission. Observing the asymmetry effects of channeling dips around the [110] axis and analyzing the asymmetry factors for host atoms and doped Zn atoms, it is revealed that almost all Zn atoms occupy the Cd sublattice sites, and Zn‐doped CdTe crystals grown by vertical Bridgman methods appear to be almost completely free from the segregation of doped Zn atoms.
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61.85.+p Channeling phenomena (blocking, energy loss, etc.)
61.72.U- Doping and impurity implantation
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients

Explosive crystallization in amorphous Si initiated by long pulse width laser irradiation

P. S. Peercy, J. Y. Tsao, S. R. Stiffler, and Michael O. Thompson

Appl. Phys. Lett. 52, 203 (1988); http://dx.doi.org/10.1063/1.99519 (3 pages) | Cited 14 times

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Explosive crystallization of amorphous Si is studied in a new heat‐flow regime using long pulse (45 ns full width at half‐maximum) ruby laser irradiation. In this regime, previously unobserved phenomena are found. Nucleation of crystalline Si is observed while the amorphous phase is melting at high (m/s) velocity and epitaxy from the underlying crystalline substrate is observed even under conditions for which the amorphous Si is never at any instant fully melted. These measurements, combined with previous measurements using short pulse irradiation, lead to development of a more complete model of explosive crystallization.
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61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
64.70.K- Solid-solid transitions

Langmuir–Blodgett film passivation of unpinned n‐type gallium arsenide surfaces

M. Tabib‐Azar, A. S. Dewa, and W. H. Ko

Appl. Phys. Lett. 52, 206 (1988); http://dx.doi.org/10.1063/1.99520 (3 pages) | Cited 7 times

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This letter reports the results of the passivation of photochemically unpinned GaAs surfaces using Langmuir–Blodgett (LB) films. Metal‐insulator‐semiconductor structures are fabricated with LB films as the insulator. The high‐frequency capacitance versus voltage measurements show an order of magnitude decrease in the interface trap density (1011 cm−2 eV−1) as compared to the GaAs/anodic oxide interface. The hysteresis in the capacitance versus voltage curves was reduced from a 3‐V shift in the flatband voltage, to about a 1‐V shift, a level which has been seen in Si/LB film metal‐insulator‐semiconductor structures. Passivation with LB films is of interest because of their interesting electrical, chemical, and optical properties that can be used in GaAs‐based devices.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
81.65.-b Surface treatments
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems
73.61.Ng Insulators

High‐quality GaInAsP/InP heterostructures grown by low‐pressure metalorganic chemical vapor deposition on silicon substrates

M. Razeghi, F. Omnes, M. Defour, and Ph. Maurel

Appl. Phys. Lett. 52, 209 (1988); http://dx.doi.org/10.1063/1.99521 (3 pages) | Cited 16 times

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High‐quality bulk InP and double heterostructure InP/GaInAsP/InP have been grown on silicon substrates by a low‐pressure metalorganic chemical vapor deposition growth technique. X‐ray diffraction patterns, as well as structural characterizations, indicate that the layers have very good crystalline quality. An intense photoluminescence signal from the quaternary alloy GaxIn1−xAsyP1−y has been recorded at room temperature, at the expected value of 1.3 μm.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
68.55.-a Thin film structure and morphology
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
78.55.Cr III-V semiconductors

Sequential tunneling due to intersubband scattering in double‐barrier resonant tunneling devices

L. Eaves, G. A. Toombs, F. W. Sheard, C. A. Payling, M. L. Leadbeater, E. S. Alves, T. J. Foster, P. E. Simmonds, M. Henini, O. H. Hughes, J. C. Portal, G. Hill, and M. A. Pate

Appl. Phys. Lett. 52, 212 (1988); http://dx.doi.org/10.1063/1.99522 (3 pages) | Cited 55 times

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Magnetoquantum oscillations in the tunnel current of double‐barrier n‐GaAs/(AlGa)As/GaAs/(AlGa)As/GaAs resonant tunneling devices reveal evidence of sequential tunneling in the voltage range corresponding to the resonance when electrons tunnel into the second subband of the GaAs quantum well. The sequential tunneling arises from intersubband scattering between two quasi‐bound states of the well. Near this resonance, the charge buildup in the well can be estimated from the magnetoquantum oscillations.
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73.40.Gk Tunneling
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.20.My Galvanomagnetic and other magnetotransport effects
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)

Photoluminescence studies of selective‐area molecular beam epitaxy of GaAs film on Si substrate

Henry P. Lee, Shyh Wang, Yi‐He Huang, and Peter Yu

Appl. Phys. Lett. 52, 215 (1988); http://dx.doi.org/10.1063/1.99523 (3 pages) | Cited 19 times

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GaAs films have been grown on Si substrates patterned with SiN by molecular beam epitaxy. The pattern consists of bare Si stripe of width ranging from 10 to 100 μm surrounded by SiN on both sides and a reference area of bare Si. 77 K photoluminescence (PL) spectrum and intensity are measured on the single crystalline GaAs films grown on these stripes and the reference area. For 1.5‐ and 3‐μm‐thick films, PL intensity from the 10 μm stripe shows 140% and 75% increase over the reference area, respectively. This remarkable increase in the PL intensity is believed due to the reduction of dislocations inside the window area. The improvement in the optical quality makes selective‐area molecular beam epitaxy a very attractive technique for the fabrication of optical devices on Si substrate.
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78.55.Cr III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Near‐ideal transport in an AlGaAs/GaAs heterostructure bipolar transistor by Na2S⋅9H2O regrowth

R. N. Nottenburg, C. J. Sandroff, D. A. Humphrey, T. H. Hollenbeck, and R. Bhat

Appl. Phys. Lett. 52, 218 (1988); http://dx.doi.org/10.1063/1.99524 (3 pages) | Cited 45 times

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The deposition of sodium sulfide nonahydrate (Na2S⋅9H2O) onto mesa AlGaAs/GaAs heterostructure bipolar transistors confers near‐ideal transport characteristics to the device structure. By reducing the GaAs surface recombination velocity, sulfide regrowth leads to current gain ( β) almost independent of collector current, and β>1 at collector current density below 5×10−7 A/cm−2. Furthermore, we obtain by passivation an emitter junction ideality factor of n=1.03.
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73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
85.30.Pq Bipolar transistors
81.65.-b Surface treatments
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Deep levels in semiconducting In‐alloyed bulk n‐GaAs and its resistivity conversions by thermal treatments

Y. Kitagawara, N. Noto, T. Takahashi, and T. Takenaka

Appl. Phys. Lett. 52, 221 (1988); http://dx.doi.org/10.1063/1.99525 (3 pages) | Cited 6 times

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Thermal conversions of resistivities have been studied for In‐alloyed semiconducting (100–106 Ω cm) n‐GaAs grown by the liquid‐encapsulated Czochralski method. These dislocation‐free as‐grown crystals are converted into semi‐insulating (>107 Ω cm) crystals by annealing at 950  °C for 2 h followed by a fast cooling. Such semi‐insulating crystals can be converted further into crystals with lower resistivities (∼106 Ω cm) by treating them at 470  °C for 100 h. In the analysis of the as‐grown samples by the temperature‐dependent Hall measurements, four levels have been found with activation energies 0.13, 0.20, 0.42, and 0.50 eV. It has been shown that these resistivity conversions are induced by concentration changes of the deep states other than the midgap donor EL2, some of them being the levels found in this study.
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71.55.Eq III-V semiconductors
81.40.Rs Electrical and magnetic properties related to treatment conditions
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
72.80.Ey III-V and II-VI semiconductors

Characterization of oval defects in molecular beam epitaxy Ga0.7Al0.3As layers by spatially resolved cathodoluminescence

A. C. Papadopoulo, F. Alexandre, and J. F. Bresse

Appl. Phys. Lett. 52, 224 (1988); http://dx.doi.org/10.1063/1.99526 (3 pages) | Cited 5 times

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Oval defects in silicon‐doped Ga0.7Al0.3As molecular beam epitaxy grown layers are studied by filtered cathodoluminescence at low temperatures (10 K) in a scanning electron microscope. The spectra obtained inside and outside the defects exhibit very different main emission lines which can be explained by an important variation of the Al/Ga ratio at the center of the defects; this hypothesis is confirmed by localized Auger electron spectroscopy.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
78.60.Hk Cathodoluminescence, ionoluminescence
78.66.Fd III-V semiconductors
78.66.Hf II-VI semiconductors

Schottky barriers of epitaxial NiSi2 on Si(111)

M. Ospelt, J. Henz, L. Flepp, and H. von Känel

Appl. Phys. Lett. 52, 227 (1988); http://dx.doi.org/10.1063/1.99527 (3 pages) | Cited 20 times

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We have investigated the Schottky‐barrier heights of high‐quality epitaxial type‐A‐ and type‐B‐oriented NiSi2 on n‐doped Si(111). Current‐voltage and photoresponse techniques have been used. The barrier height of type‐A NiSi2 is found to be low (0.64 eV), whereas type‐B NiSi2 yields a high barrier of 0.76 eV. Ideality factors very close to unity (1.00–1.02) have been observed both for type‐A NiSi2 as well as for type B.
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73.30.+y Surface double layers, Schottky barriers, and work functions
73.40.Ns Metal-nonmetal contacts

Epitaxial GexSi1−x/Si (100) structures produced by pulsed laser mixing of evaporated Ge on Si (100) substrates

John R. Abelson, Thomas W. Sigmon, Ki Bum Kim, and Kurt H. Weiner

Appl. Phys. Lett. 52, 230 (1988); http://dx.doi.org/10.1063/1.99528 (3 pages) | Cited 48 times

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Heteroepitaxial GexSi1−x alloy layers have been formed by pulsed laser induced mixing of pure germanium films and Si (100) substrates. Ge films 50–200 Å thick are electron beam evaporated onto Si (100) under ≤1×10−7 Torr vacuum. The near surface of the sample then undergoes a rapid melt and regrowth process using 2–10 pulses from a XeCl excimer laser. The laser has a 37‐ns pulse width at 308 nm and its energy density of 0.5–1.5 J/cm2 is precisely homogenized into a 4×4 mm square area. The alloy layers are 250–1600 Å thick, have a Ge fraction x=2.5–19%, and exhibit excellent crystallinity as evaluated by MeV ion channeling and lattice resolution cross‐sectional transmission electron microscopy. Unlike layer growth by molecular beam epitaxy, this approach is insensitive to minor levels of contamination because the original Ge/Si interface is melted through during the laser processing.
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81.15.Np Solid phase epitaxy; growth from solid phases
68.35.Fx Diffusion; interface formation
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.55.-a Thin film structure and morphology

Free‐electron laser study of the nonlinear magnetophotoconductivity in n‐GaAs

J. Kaminski, J. Spector, W. Prettl, and M. Weispfenning

Appl. Phys. Lett. 52, 233 (1988); http://dx.doi.org/10.1063/1.99506 (3 pages) | Cited 11 times

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The University of California at Santa Barbara free‐electron laser was used to investigate the kinetics of electrons bound to shallow donors in n‐GaAs by saturation spectroscopy. The resonant photothermal conductivity arising from 1s–2p+ shallow donor excitations in a magnetic field was measured at intensities greatly exceeding that of earlier investigations and saturation of bound‐to‐free photoionization transitions was achieved. The impurity resonance photoconductive signal shows a distinct intensity dependence caused by competing bound‐to‐free transitions which saturate differently. This permits a more detailed evaluation of the electron recombination kinetics than was previously possible, yielding the ionization probability of the 2p+ state, the transition time of electrons from the 2p+ level to the gound state, and the recombination time of free carriers.
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72.40.+w Photoconduction and photovoltaic effects
72.20.My Galvanomagnetic and other magnetotransport effects
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Inelastic scattering of electrons traversing semiconductor heterojunctions

J. F. Müller, S. Schmitt‐Rink, and A. F. J. Levi

Appl. Phys. Lett. 52, 236 (1988); http://dx.doi.org/10.1063/1.99507 (3 pages) | Cited 5 times

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We calculate the contribution of polar optic phonons to the inelastic scattering rate for an electron traversing semiconductor heterojunctions. In typical geometries, a dramatic reduction in scattering rate compared to the bulk value is found for a limited range of electron energies. This effect is related to spatial separation of initial and final electron wave functions either side of the heterojunction caused by quantum mechanical reflection at the interface. The influence of this phenomenon on the performance of devices, such as unipolar hot‐electron transistors, is discussed.
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72.20.Dp General theory, scattering mechanisms
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
85.30.De Semiconductor-device characterization, design, and modeling
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Surface compositional and topographical changes resulting from excimer laser impacting on YBa2Cu3O7 single phase superconductors

O. Auciello, A. R. Krauss, J. Santiago‐Aviles, A. F. Schreiner, and D. M. Gruen

Appl. Phys. Lett. 52, 239 (1988); http://dx.doi.org/10.1063/1.99508 (3 pages) | Cited 27 times

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Superconducting pressed pellets of YBa2Cu3O7 (Tc=90 K), which were used as ablation targets for laser‐induced vapor deposition of high Tc(85 K) superconducting thin films, have been analyzed by secondary electron microscopy, scanning Auger microscopy, energy dispersive x‐ray analysis, and x‐ray diffractometry. The elemental distribution of Y, Ba, and Cu appears reasonably uniform at depths corresponding to that probed by energy dispersive x‐ray analysis (∼1 μm). However, scanning Auger microscopy analysis of the laser‐impacted area shows a significant depletion of Cu and spatial redistribution of Y, Ba, Cu, and O on the target surface. X‐ray diffractometry of the laser‐impacted area shows the appearance of a new broad peak at a diffraction angle 2θ=29.7°, characteristic of BaY2O4 and a poorly defined peak at 2θ=29.3°, that can be attributed to BaCuO2. A possible influence of the laser‐induced bulk superconductor compositional changes on the film composition is discussed in relation to recently reported experimental results on laser vapor deposition of high Tc films.
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68.35.Dv Composition, segregation; defects and impurities
68.55.Nq Composition and phase identification
68.35.B- Structure of clean surfaces (and surface reconstruction)
74.70.-b Superconducting materials other than cuprates

Raman spectroscopic investigation of superconducting YBa2Cu3O7−x, semiconducting YBa2Cu3O6+x, and possible impurity phases

A. Mascarenhas, S. Geller, L. C. Xu, H. Katayama‐Yoshida, J. I. Pankove, and S. K. Deb

Appl. Phys. Lett. 52, 242 (1988); http://dx.doi.org/10.1063/1.99651 (2 pages) | Cited 11 times

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A Raman spectroscopic investigation of specimens of superconducting YBa2Cu3O7−x and of the possible impurity phases YBa2Cu3O6+x (semiconductor), Y2BaCuO5, Y2Cu2O5, BaCuO2, CuO, Y2O3, and BaCO3 indicates that in the range 100–700 cm−1, there are six characteristic lines belonging to the superconductor. At 13 K, these lines are at 150, 338, 441, 507, 590, and 644 cm−1. Comparison of the Raman spectra of the superconductor and the semiconductor indicates a mode stiffening of the pair at 338 and 441 cm−1, but a mode softening of the pair at 507 and 590 cm−1. A factor group analysis leads to a tentative assignment of the Raman and infrared allowed modes.
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78.30.Hv Other nonmetallic inorganics
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients
74.70.-b Superconducting materials other than cuprates

High‐resolution magnetic imaging of domains in TbFe by force microscopy

Y. Martin, D. Rugar, and H. K. Wickramasinghe

Appl. Phys. Lett. 52, 244 (1988); http://dx.doi.org/10.1063/1.99482 (3 pages) | Cited 77 times

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High‐resolution images of domains written in a magnetic thin film have been obtained for the first time using force microscopy. The sample consisted of 500‐Å‐thick Tb19Fe81 with magnetization of 109 emu/cm3. Micron‐sized magnetic domains were thermomagnetically written in the sample using a focused laser beam. Domain images were obtained by observing the magnetic interaction of the sample with a small vibrating magnetized iron tip. Typical observed force gradients were in the range 0.8×10−4–6×10−4 N/m and the forces were in the range 10−12–10−11 N. The spatial resolution of the technique was on the order of 1000 Å. This was sufficient resolution to see irregularities in those laser written marks which were recorded using low bias field.
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75.70.Kw Domain structure (including magnetic bubbles and vortices)
75.50.Bb Fe and its alloys
75.50.Gg Ferrimagnetics
85.70.Sq Magnetooptical devices
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