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26 Dec 1988

Volume 53, Issue 26, pp. 2579-2719

Page 2 of 2 Pages Previous Page | Jump to Page

Isoelectronic doping in GaAs epilayers grown by molecular beam epitaxy

M. K. Lee, T. H. Chiu, A. Dayem, and E. Agyekum

Appl. Phys. Lett. 53, 2653 (1988); http://dx.doi.org/10.1063/1.100184 (3 pages) | Cited 9 times

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In‐doped GaAs epilayers have been grown by molecular beam epitaxy. This work investigates the relatively unexplored In doping concentration in the range of 1017–1019 cm−3. Enhancement in Hall mobility and photoluminescence intensity have been observed. Proper isoelectronic doping may lead to reduction of the unintentional impurity level.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
78.55.Cr III-V semiconductors
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)

Faraday rotation in the 10 μm region in InSb at liquid‐helium temperature

R. L. Aggarwal, R. F. Lucey, and D. P. Ryan‐Howard

Appl. Phys. Lett. 53, 2656 (1988); http://dx.doi.org/10.1063/1.100185 (3 pages) | Cited 3 times

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Faraday rotation has been measured at 10.59 and 9.66 μm in n‐type InSb at ∼6 K having a carrier concentration of ∼2×1014 cm−3, using magnetic fields up to 50 kG. In addition to the interband and free‐carrier plasma contributions to the Faraday rotation, an appreciable contribution from the conduction electron spins has been observed. The latter contribution is proportional to the spin alignment that saturates at magnetic fields exceeding ∼5 kG. Its saturation value of −17±1°/cm at 10.59 μm is in good agreement with the value calculated from published theoretical results. A value of −1.8±0.1°/kG cm has been deduced for the interband contribution at 10.59 μm, in disagreement with the previously published value of −3.8°/kG cm. Design for a 10 μm Faraday isolator is proposed for operation at ∼5 kG, a field well within the range of permanent magnets.
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78.20.Ls Magneto-optical effects

Temperature dependence of interstitial oxygen diffusion in antimony‐doped Czochralski silicon

A. S. Oates and W. Lin

Appl. Phys. Lett. 53, 2659 (1988); http://dx.doi.org/10.1063/1.100186 (2 pages) | Cited 6 times

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We have measured directly the diffusivity of interstitial oxygen in Sb‐doped Czochralski silicon in the temperature range 750–1150 °C. Using secondary‐ion mass spectroscopy of outdiffusion profiles, we show that the diffusivity is the same as that for lightly B‐doped crystals heated under identical conditions over the temperature range studied. We briefly discuss the implication of these results upon oxygen precipitation mechanisms in Sb‐doped silicon.
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66.30.J- Diffusion of impurities
61.72.jd Vacancies
61.72.jj Interstitials
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients

Carbon doping in molecular beam epitaxy of GaAs from a heated graphite filament

R. J. Malik, R. N. Nottenberg, E. F. Schubert, J. F. Walker, and R. W. Ryan

Appl. Phys. Lett. 53, 2661 (1988); http://dx.doi.org/10.1063/1.100187 (3 pages) | Cited 71 times

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Carbon doping of GaAs grown by molecular beam epitaxy has been obtained for the first time by use of a heated graphite filament. Controlled carbon acceptor concentrations over the range of 1017–1020 cm−3 were achieved by resistively heating a graphite filament with a direct current power supply. Capacitance‐voltage, p/n junction, and secondary‐ion mass spectrometry measurements indicate that there is negligible diffusion of carbon during growth and with post‐growth rapid thermal annealing. Carbon was used for p‐type doping in the base of Npn AlGaAs/GaAs heterojunction bipolar transistors. Current gains greater than 100 and near‐ideal emitter heterojunctions were obtained in transistors with a carbon base doping of 1×1019 cm−3. These preliminary results indicate that carbon doping from a solid graphite source may be an attractive substitute for beryllium which is known to have a relatively high diffusion coefficient in GaAs.
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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
85.30.Pq Bipolar transistors
73.61.Ey III-V semiconductors

Growth of GaAs‐Al‐GaAs by migration‐enhanced epitaxy

Bijan Tadayon, Saied Tadayon, M. G. Spencer, G. L. Harris, L. Rathbun, J. T. Bradshaw, W. J. Schaff, P. J. Tasker, and L. F. Eastman

Appl. Phys. Lett. 53, 2664 (1988); http://dx.doi.org/10.1063/1.100188 (2 pages) | Cited 5 times

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The GaAs‐Al‐GaAs structure is grown using migration‐enhanced epitaxy (MEE) method at low temperature on a molecular beam epitaxy machine. With MEE the interdiffusion between Al and GaAs is reduced by a large amount, and the morphology is improved by a large degree. Still, Raman spectrum indicates poor crystallinity for the GaAs of the top layer. The effect of different annealing temperatures on the interdiffusion is also studied.
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81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties
68.55.-a Thin film structure and morphology
78.30.Fs III-V and II-VI semiconductors

Miniband dispersion in GaAs/AlxGa1−xAs superlattices with wide wells and very thin barriers

M. W. Peterson, J. A. Turner, C. A. Parsons, A. J. Nozik, D. J. Arent, C. Van Hoof, G. Borghs, R. Houdré, and H. Morkoç

Appl. Phys. Lett. 53, 2666 (1988); http://dx.doi.org/10.1063/1.100189 (3 pages) | Cited 8 times

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Photoreflectance spectra have been used to characterize miniband formation in GaAs/ Alx Ga1−x As superlattices with wide wells (275–255 Å) and withb arriers as thin as 17 Å. Thirty‐two optical transitions are resolved in the photoreflectance spectra of the 17 Å barrier sample. These experimental transitions match all those theoretically predicted from the selection rule Δn=0, including Γ‐ and Π‐type transitions arising from miniband dispersion; these results imply sample perfection. A sample with a 40 Å barrier exhibits forbidden transitions with Δn≠0; these additional transitions, together with the narrow width of the minibands for 40 Å barriers, create difficulty in resolving the miniband structure.
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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
78.66.Hf II-VI semiconductors

Unified planar process for fabricating heterojunction bipolar transistors and buried‐heterostructure lasers utilizing impurity‐induced disordering

R. L. Thornton, W. J. Mosby, and H. F. Chung

Appl. Phys. Lett. 53, 2669 (1988); http://dx.doi.org/10.1063/1.100192 (3 pages) | Cited 8 times

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We describe results on a novel geometry of heterojunction bipolar transistor that has been realized by impurity‐induced disordering. This structure is fabricated by a method that is compatible with techniques for the fabrication of low threshold current buried‐heterostructure lasers. We have demonstrated this compatibility by fabricating a hybrid laser/transistor structure that operates as a laser with a threshold current of 6 mA at room temperature, and as a transistor with a current gain of 5.
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85.30.Pq Bipolar transistors
42.55.Px Semiconductor lasers; laser diodes
68.35.Fx Diffusion; interface formation
42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Properties of p+ microcrystalline films of SiC:H deposited by conventional rf glow discharge

B. Goldstein, C. R. Dickson, I. H. Campbell, and P. M. Fauchet

Appl. Phys. Lett. 53, 2672 (1988); http://dx.doi.org/10.1063/1.100193 (3 pages) | Cited 25 times

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Using a conventional rf glow discharge, we have grown microcrystalline p+ SiC:H films having conductivities 2–2×10−3 (Ω cm)−1 and activation energies 0.05–0.1 eV with carbon concentrations 0–6 at. %, respectively. Increasing the carbon content suppresses the microcrystallinity. The choice of substrate is crucial to initiating the immediate onset of microcrystalline growth in thin (∼200–400 Å) films.
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81.15.Rs Spray coating techniques
73.61.Cw Elemental semiconductors
73.61.Jc Amorphous semiconductors; glasses
73.61.Le Other inorganic semiconductors
68.55.-a Thin film structure and morphology
68.55.Nq Composition and phase identification

High Tc Y‐Ba‐Cu‐O thin films by ion beam sputtering

J. Gao, Y. Z. Zhang, B. R. Zhao, P. Out, C. W. Yuan, and L. Li

Appl. Phys. Lett. 53, 2675 (1988); http://dx.doi.org/10.1063/1.100542 (2 pages) | Cited 4 times

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High quality Y‐Ba‐Cu‐O thin films were successfully prepared by using ion beam sputtering. Zero resistance was reached at 90 K. The critical current density at 77 K was 4–5×104 A/cm2. The surface morphology of the films was observed by scanning electron microscopy.
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81.15.Cd Deposition by sputtering
74.25.Sv Critical currents
74.78.-w Superconducting films and low-dimensional structures
68.55.-a Thin film structure and morphology

Low‐loss substrate for epitaxial growth of high‐temperature superconductor thin films

R. W. Simon, C. E. Platt, A. E. Lee, G. S. Lee, K. P. Daly, M. S. Wire, J. A. Luine, and M. Urbanik

Appl. Phys. Lett. 53, 2677 (1988); http://dx.doi.org/10.1063/1.100543 (3 pages) | Cited 123 times

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A perovskite‐like single‐crystal substrate material has been investigated that simultaneously permits epitaxial growth of 1‐2‐3 superconductor films and possesses desirable rf properties of low dielectric constant and loss tangent. The lattice constant of 3.792 Å provides a lattice match to within 1% of the a axis of 1‐2‐3. Sputtered films of erbium‐barium‐copper‐oxide have been produced on (100) LaAlO3 substrates that exhibit sharp resistive transitions at 90 K (ΔT=1K), bulk superconductivity as determined by ac susceptibility measurements, and nearly single‐crystal growth as evidenced by x‐ray diffraction and high‐resolution scanning electron microscopy. The high‐frequency dielectric properties of LaAlO3 were experimentally investigated at several temperatures. The low‐frequency dielectric constant was measured to be 15 and the microwave loss tangent ranged from 6×10−4 at room temperature to 5×10−6 at 4 K.
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74.78.-w Superconducting films and low-dimensional structures
68.55.-a Thin film structure and morphology
77.22.Ch Permittivity (dielectric function)
74.70.-b Superconducting materials other than cuprates

Investigation of harmonic generation in the alternating magnetic response of superconducting Y‐Ba‐Cu‐O

A. Shaulov and D. Dorman

Appl. Phys. Lett. 53, 2680 (1988); http://dx.doi.org/10.1063/1.100544 (3 pages) | Cited 47 times

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The magnetic behavior of a sintered Y‐Ba‐Cu‐O superconductor has been investigated by monitoring the harmonic components of its magnetic response to an alternating field. As the steady bias field is incrementally raised, a transition from a linear, reversible behavior of the magnetization to a nonlinear, irreversible behavior is indicated by the appearance of magnetic losses and odd harmonic components in the response. These harmonics disappear as the bias field or the temperature is increased above a certain point, indicating a linear behavior. The disappearance of the odd harmonics, while the magnetic losses persist, is interpreted as signifying a transition to a state of dissipative flux motion without pinning. These measurements demonstrate a new technique for determination of the lower critical field and the ‘‘irreversibility’’ field below which irreversibility in the magnetization sets in as a result of flux pinning.
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74.25.Op Mixed states, critical fields, and surface sheaths
74.70.-b Superconducting materials other than cuprates
74.25.N- Response to electromagnetic fields
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)

In situ epitaxial growth of Y1Ba2Cu3O7−x films by molecular beam epitaxy with an activated oxygen source

J. Kwo, M. Hong, D. J. Trevor, R. M. Fleming, A. E. White, R. C. Farrow, A. R. Kortan, and K. T. Short

Appl. Phys. Lett. 53, 2683 (1988); http://dx.doi.org/10.1063/1.100545 (3 pages) | Cited 74 times

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Highly oriented, epitaxial Y1Ba2Cu3O7−x thin films were prepared on MgO(100) by molecular beam epitaxy at a substrate temperature of 550–600 °C. The in situ growth was achieved by incorporating reactive oxygen species produced by a remote microwave plasma in a flow‐tube reactor. The epitaxial (001) orientation is demonstrated by x‐ray diffraction and ion channeling. In situ reflection high‐energy electron diffraction showed that a layer‐by‐layer growth has produced a well‐ordered, atomically smooth surface in the as‐grown tetragonal phase of an oxygen stoichiometry of 6.2–6.3. A 500 °C anneal in 1 atm of O2 converted the oxygen content to 6.7 to 6.8. Typical superconducting transport properties of an Y1Ba2Cu3O7−x film 1000 Å thick are ρ(300 K)=325 μΩ cm, ρ(300 K)/ρ(100 K)=2.4, Tc(onset)=92 K, and Tc(R=0)=82 K. The transport Jc at 75 K is 1×105 A/cm2, and increases to 1×106 A/cm2 at 70 K.
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74.70.-b Superconducting materials other than cuprates
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
74.78.-w Superconducting films and low-dimensional structures
74.25.Sv Critical currents

Tl2O3 vapor process of making Tl‐Ba‐Ca‐Cu‐O superconductors

Z. Z. Sheng, L. Sheng, H. M. Su, and A. M. Hermann

Appl. Phys. Lett. 53, 2686 (1988); http://dx.doi.org/10.1063/1.100670 (3 pages) | Cited 17 times

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A new process for making Tl‐Ba‐Ca‐Cu‐O superconductors which is based on reactions between solid precursor Ba‐Ca‐Cu‐oxides and vapor Tl2O3 has been developed. The Tl2O3 vapor process allows Tl‐Ba‐Ca‐Cu‐O superconductors to be easily made in the forms of complex bulk components, wires and fibers, and thick and thin films, and minimizes problems caused by toxicity and volatility of Tl starting compounds.
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74.70.-b Superconducting materials other than cuprates
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
81.10.-h Methods of crystal growth; physics and chemistry of crystal growth, crystal morphology, and orientation
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Tunnel junctions using oxide superconducting thin films epitaxially grown on SrTiO3

J. Takada, T. Terashima, Y. Bando, H. Mazaki, K. Iijima, K. Yamamoto, and K. Hirata

Appl. Phys. Lett. 53, 2689 (1988); http://dx.doi.org/10.1063/1.100546 (3 pages) | Cited 6 times

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Normal‐metal/insulator/superconductor (NIS) junctions were fabricated using thin films of YBa2Cu3O7−x (YBCO) or ErBa2Cu3O7−x. These were epitaxially grown on single‐crystal SrTiO3 by the activated reactive evaporation method. For some NIS junctions prepared on SrTiO3 (110) substrates, we observed multipeaks in the differential conductance versus voltage curve. NIS junctions using single‐crystal YBCO films on SrTiO3 (100) showed a set of peaks, from which we obtained a gap parameter of 11.5±1.5 meV at 4.4 K and a coupling constant of 3.2±0.4.
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74.50.+r Tunneling phenomena; Josephson effects
74.78.-w Superconducting films and low-dimensional structures
74.70.-b Superconducting materials other than cuprates
73.40.-c Electronic transport in interface structures

Nonaqueous chemical etch for YBa2Cu3O7−x

R. P. Vasquez, B. D. Hunt, and M. C. Foote

Appl. Phys. Lett. 53, 2692 (1988); http://dx.doi.org/10.1063/1.100547 (3 pages) | Cited 58 times

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A nonaqueous chemical etch, with Br as the active ingredient, is described which removes the insulating hydroxides and carbonates that form on high‐temperature superconductor surfaces as a result of atmospheric exposure. X‐ray photoemission spectra have been recorded before and after etching YBa2Cu3O7−x films. It is found that, after the etch, the high binding energy O 1s and Ba 3d peaks associated with surface contaminants are greatly reduced, the Y:Ba:Cu ratio is close to the expected 1:2:3, and the oxidation state of the Cu(2+) is not affected. The resistance of an etched film reaches zero at 78 K, compared to 81 K for a similar unetched film. The suitability of other nonaqueous halogen‐based etches is discussed, as is the applicability of this etch to other high Tc superconductors.
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81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
81.65.-b Surface treatments
74.78.-w Superconducting films and low-dimensional structures
74.70.-b Superconducting materials other than cuprates
79.60.-i Photoemission and photoelectron spectra

Vanishing of superconductivity at a transition from itinerant‐electron to small‐polaron conduction in nominal Bi4−xPbx(Sr3Ca)Ca2−xYxCu4O16

A. Manthiram and J. B. Goodenough

Appl. Phys. Lett. 53, 2695 (1988); http://dx.doi.org/10.1063/1.100548 (3 pages) | Cited 8 times

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Lead was found to substitute for bismuth on cosubstitution of yttrium for calcium in nominal Bi4(Sr3Ca)Ca2Cu4O16. Variations with x in the lattice parameters, the oxidation parameter determined by iodometric titration, and the temperature dependence of resistance have revealed a correlation of the variation of Tc and c parameter versus x with a metal‐to‐semiconductor transition. It is argued that this correlation manifests a transition from itinerant‐electron to small‐polaron conduction. This conclusion is related to the observed shifts in c‐axis oxygen that appear to be associated with a transition from antiferromagnetic semiconductor to a superconductor in other copper‐oxide systems.
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74.78.Fk Multilayers, superlattices, heterostructures
74.20.Mn Nonconventional mechanisms
74.20.Rp Pairing symmetries (other than s-wave)
74.25.Sv Critical currents
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition
71.38.-k Polarons and electron-phonon interactions

Emission spectra from ArF laser ablation of high Tc superconductor Bi2CaSr2Cu2O9

Subhash Deshmukh, Erhard W. Rothe, Gene P. Reck, T. Kushida, and Zai Gui Xu

Appl. Phys. Lett. 53, 2698 (1988); http://dx.doi.org/10.1063/1.100549 (3 pages) | Cited 23 times

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A 193 nm excimer laser is used to ablate a Bi2CaSr2Cu2O9 superconductor and samples of Bi2O3, CaO, CuO, and Sr(OH)2⋅8H2O. Emission spectra generated during ablation are presented. These emissions are from simple atomic and diatomic species. Our observations show that the emission can be used to characterize the bulk material.
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79.20.Ds Laser-beam impact phenomena
74.70.-b Superconducting materials other than cuprates
78.40.Ha Other nonmetallic inorganics
74.78.-w Superconducting films and low-dimensional structures

Real‐time monitoring of laser ablation deposition of superconductors by fluorescence and secondary‐ion spectra

C. H. Chen, M. P. McCann, and R. C. Phillips

Appl. Phys. Lett. 53, 2701 (1988); http://dx.doi.org/10.1063/1.100550 (3 pages) | Cited 29 times

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Fluorescence spectra and secondary‐ion spectra for laser ablation of high‐temperature metal‐oxide superconductors are reported. These processes can be used to monitor a thin‐film deposition process. The fluorescence spectra are more suitable for Y, Ba, and Ca ions. However, ion spectra can be used to monitor and identify Tl and Ca ions easier than by fluorescence spectra.
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74.78.-w Superconducting films and low-dimensional structures
74.70.-b Superconducting materials other than cuprates
81.15.Jj Ion and electron beam-assisted deposition; ion plating
79.20.Ds Laser-beam impact phenomena

High Tc superconducting film as a fast nonlinear switch for noise discrimination in digital circuits

A. Frenkel, T. Venkatesan, Chinlon Lin, X. D. Wu, M. S. Hegde, A. Inam, and B. Dutta

Appl. Phys. Lett. 53, 2704 (1988); http://dx.doi.org/10.1063/1.100551 (3 pages) | Cited 11 times

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Measurements of fast nonlinear switching of a high Tc superconducting thin film at 70 K between the dissipative state (induced by an electrical current) and superconducting state are reported. System rise and fall times are measured to be about 1 ns and are limited by the parasitic components of the electrical circuitry. A novel scheme for noise discrimination in digital circuits using this switching has been proposed and experimentally demonstrated for speeds exceeding 200 Mb/s. This method allows significant reduction of amplitude noise and improvement of signal‐to‐noise ratio in digital circuits.
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85.25.Qc Superconducting surface acoustic wave devices and other superconducting devices
74.70.-b Superconducting materials other than cuprates
74.40.-n Fluctuation phenomena
84.30.-r Electronic circuits

Electrochemical method of determination of the valence states of copper in YBaCuO compounds

S. Salkalachen, E. Salkalachen, P. K. John, and H. R. Froelich

Appl. Phys. Lett. 53, 2707 (1988); http://dx.doi.org/10.1063/1.100552 (3 pages) | Cited 1 time

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We describe an electrochemical technique to measure the oxidation states of copper in thin‐film YBaCuO compounds. Quantitative information is obtained on Cu+ and Cu++ species.
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74.70.-b Superconducting materials other than cuprates
74.78.-w Superconducting films and low-dimensional structures
82.80.Fk Electrochemical methods
71.70.-d Level splitting and interactions

Thermodynamic studies of the orthorhombic–tetragonal transition in Ba2YCu3O7−δ

W. Lo, Tong B. Tang, Chaorui Li, and Yuhuan Xu

Appl. Phys. Lett. 53, 2710 (1988); http://dx.doi.org/10.1063/1.100553 (3 pages) | Cited 1 time

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The superconducting oxide Ba2YCu3O7−δ is known to exist in two crystallographic structures, being orthorhombic or, at higher temperature, tetragonal. Thermogravimetric experiments have been performed to study their transition at different oxygen partial pressures. Weight loss curves, recorded by heating samples at various constant rates, each exhibit two inflection points. In our interpretation, such points delimit the regime within which the two structural phases coexist. Limiting values of temperature at these points, calculated by extrapolation to zero heating rates, and the corresponding magnitudes of oxygen nonstoichiometry are presented. Such data have basic significance as well as relevance to the thermal processing of materials.
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64.70.K- Solid-solid transitions
74.70.-b Superconducting materials other than cuprates
65.20.-w Thermal properties of liquids
65.40.gd Entropy

Absence of chain oxygen outgassing from ion‐bombarded YBa2Cu3O7−x

A. D. Marwick, C. Richard Guarnieri, and J. M. Manoyan

Appl. Phys. Lett. 53, 2713 (1988); http://dx.doi.org/10.1063/1.100554 (2 pages) | Cited 8 times

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We report an investigation of possible oxygen loss from an ion‐bombarded YBa2Cu3O7−x superconductor. The chain oxygen sites in thin‐film samples were filled with 18O, and the 18O content of the films measured as a function of irradiating ion dose using the 18O(p,α)15N nuclear reaction. Absolute measurement of the 18O concentration was achieved by the use of a Si18O2 standard. No significant change in the 18O concentration was detected after irradiation with 2×1014 2 MeV As ions/cm2, which is a dose sufficient to raise the resistivity of the samples by a factor of 104. We conclude that ion irradiation does not cause oxygen to outgas from the chain sites. This implies that ion bombardment effects in YBa2Cu3O7−x are due to radiation‐induced defects.
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74.70.-b Superconducting materials other than cuprates
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
74.78.-w Superconducting films and low-dimensional structures
61.80.Jh Ion radiation effects

Measurement of opaque coating thickness using photothermal radiometry

S. J. Sheard and M. G. Somekh

Appl. Phys. Lett. 53, 2715 (1988); http://dx.doi.org/10.1063/1.100161 (2 pages) | Cited 4 times

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We describe a method for determination of film thickness using the photothermal radiometric microscope. The method is noncontacting and nondestructive, and is applicable to coatings covering the entire surface of the material. The frequency variation of both the amplitude and phase of the thermal wave response is used to determine the film thickness. This gives two independent measures. The technique is valid regardless of the properties of the substrate material, but is more accurate when these differ substantially from those of the coating.
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81.70.-q Methods of materials testing and analysis
07.60.Dq Photometers, radiometers, and colorimeters

Deposition and imaging of localized charge on insulator surfaces using a force microscope

J. E. Stern, B. D. Terris, H. J. Mamin, and D. Rugar

Appl. Phys. Lett. 53, 2717 (1988); http://dx.doi.org/10.1063/1.100162 (3 pages) | Cited 128 times

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A force microscope has been used in a new application to deposit and image localized surface charge on insulators. The lateral resolution for imaging surpasses that of currently available techniques. By applying voltage pulses to an etched nickel microscope tip, micron‐sized regions of approximately 2×10−16 C were created on polymethylmethacrylate and single‐crystal sapphire surfaces. After depositing the charge, high‐contrast images of the charged region were obtained as contours of constant force gradient. The contrast was observed to decay over approximately 1 h, providing evidence for surface charge mobility. The minimum detectable surface charge was estimated to be on the order of 100 electrons.
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73.25.+i Surface conductivity and carrier phenomena
73.40.-c Electronic transport in interface structures
07.79.Cz Scanning tunneling microscopes
61.05.-a Techniques for structure determination
73.61.Ng Insulators
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