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  • 1
    Electronic Resource
    Electronic Resource
    An investigation of the Pd-In-Ge nonspiking Ohmic contact to n-GaAs using transmission line measurement, Kelvin, and Cox and Strack structures (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 4364-4372 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Pd-In-Ge nonspiking Ohmic contact to n-GaAs has been investigated using the transmission line, the Kelvin, and the Cox and Strack structures. It has been found that a layered structure of Pd/In/Pd/n-GaAs with 10–20 A(ring) of Ge imbedded in the Pd layer adjacent to the GaAs can lead to a hybrid contact. When the Ohmic formation temperature is above 550 °C, a layer of InxGa1−xAs doped with Ge is formed between the GaAs structure and the metallization. When the Ohmic formation temperature is below 550 °C, a regrown layer of GaAs also doped with Ge is formed at the metallization/GaAs interface. The contact resistivity of 2–3×10−7 Ω cm2 for this contact structure is nearly independent of the contact area from 900 to 0.2 μm2. Low-temperature Ohmic characteristics and thermal stability are also examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348360
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  • 2
    Electronic Resource
    Electronic Resource
    Electron optical design of a high-resolution low-voltage scanning electron microscope with field emission gun (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2905-2910 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In the present study, a comprehensive description and a complete process for designing a high-resolution low-voltage scanning electron microscope with a field emission gun have been discussed, including the design of two types of magnetic immersion lenses optimized for low-voltage operation, the evaluation of their resolution, the design of the magnetic lens/secondary electron collector system, the calculation of three-dimensional trajectories for both secondary electrons and backscattered electrons, and the estimate of their collection efficiency. The computed results and the primary experiments indicate the possibility of achieving nanometer resolution, which basically approaches the electron optical predictable probe size for the low-voltage scanning electron microscope.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144381
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  • 3
    Electronic Resource
    Electronic Resource
    High-resolution low-voltage electron optical system for very large specimens (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 3434-3441 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This article introduces an unconventional electron optical probe forming system which is particularly suitable for low beam voltages and very large specimens, such as semiconductor wafers which also require a large angle tilting. The system can produce an electron probe of less than 20 A(ring) for a nontilting specimen at 1-kV beam voltage with a working distance of 2.5 mm. The particular design allows a large volume of free space below the specimen which may be used to accommodate a complicated transporting mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140541
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  • 4
    Electronic Resource
    Electronic Resource
    Strain-induced confinement of carriers to quantum wires and dots within an InGaAs-InP quantum well (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 681-683 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe a novel method of confining carriers by deliberately creating large inhomogeneous strain patterns in a quantum well. The strain modulates the band gap to provide lateral quantum confinement for excitons. Here, we generate strain confinement in an InGaAs quantum well by reactive ion beam assisted etching through an overlying compressed pseudomorphic quaternary layer using etch masks patterned by electron beam lithography. Photoluminescence spectra of arrays of wires and dots show red-shifted band gaps in direct evidence of lateral confinement. We compare our results to finite element calculations of the inhomogeneous strain in an InP substrate from a compressed overlayer patterned into rectangular wires.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102266
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  • 5
    Electronic Resource
    Electronic Resource
    Formation of laterally propagating supersteps of InP/InGaAs on vicinal wafers (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 472-474 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We propose and demonstrate a technique for artifically bunching the atomic steps on a vicinal substrate to form supersteps of almost arbitrary height. The process involves the etching of a grating of parallel grooves on the surface of a vicinal substrate followed by epitaxial growth that fills the grooves. Steps of height proportional to the period of the grating and the substrate misorientation angle are formed. The technique is demonstrated on a macroscopic scale for the InP/InGaAs material system using chloride transport vapor levitation epitaxy, resulting in InGaAs wire-like structures confined both horizontally and vertically by InP. The growth of quantum wires and laterally periodic superlattices should be possible using this technique with proper scaling of parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101856
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  • 6
    Electronic Resource
    Electronic Resource
    Generation of macroscopic steps on patterned (100) vicinal GaAs surfaces (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 867-869 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We show that macroscopic, as opposed to microscopic, steps can be obtained on a semiconductor vicinal surface when a perturbation has been "printed'' on it, prior to epitaxial growth. This generic crystal growth concept has been studied here with the GaAs/AlGaAs system using organometallic chemical vapor deposition. The details of step formation, stabilization, and subsequent propagation have been investigated with scanning electron microscopy. Regular, sawtooth-like growth patterns have been obtained, with periodic growth rate differences at the step edges. This novel lateral patterning technique was employed to fabricate arrays of quantum wire-like heterostructures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101624
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  • 7
    Electronic Resource
    Electronic Resource
    Imaging of current-induced superconducting-resistive transitions by scanning electron microscopy in laser-deposited superconducting thin films of Y1Ba2Cu3O7−x (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 911-913 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the transport current-induced resistive transitions in predominantly c-axis oriented crystalline Y1Ba2Cu3O7−x superconducting thin films with scanning electron microscopic (SEM) imaging and its correlation with dc current-voltage (I-V) measurements. We find that there is a nonlinear gradual transition region in the I-V curves that is caused by macroscopic effects (current "crowding'', substrate defects, film thickness variation, etc.) and by microscopic dissipation effects. At a high current there is an abrupt transition to the normal state in the I-V curve due to Joule heating. The SEM mapping provides a direct image of the above effects and is useful for characterization and study of fundamental transport properties of high Tc thin films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101620
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  • 8
    Electronic Resource
    Electronic Resource
    Picosecond temporal resolution photoemissive sampling (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 358-360 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Sampling measurements of electrical transients generated photoconductively on a 5-μm gold coplanar transmission line on GaAs were performed via multiphoton photoemission. A temporal resolution of 5 ps was achieved, with a voltage sensitivity of 10 mV/(Hz)1/2. These results confirm that the temporal resolution attainable by this technique is enhanced when the dimensions of the structure under examination are reduced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98440
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  • 9
    Electronic Resource
    Electronic Resource
    Growth of GaAs quantum wire arrays by organometallic chemical vapor deposition on submicron gratings (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 914-916 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the growth of dense lateral arrays of GaAs quantum wire structures, obtained by organometallic chemical vapor deposition (OMCVD) on GaAs substrates where a submicron grating has been lithographically defined and etched prior to deposition. The experiments were performed simultaneously on (100) oriented substrates, where the wires are virtually "isolated'' from each other, and on substrates that are vicinal with respect to the (100) orientation, where the wires are "smoothly connected'' by quantum wells. Transmission electron microscopy investigations allowed the study of the morphology of the resulting structures, which was related to the microscopic step nature of the starting surfaces and revealed important basic aspects of growth dynamics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103384
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  • 10
    Electronic Resource
    Electronic Resource
    Positive and negative "resistless'' lithography of GaAs by electron beam exposure and thermal Cl2 etching (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 1043-1045 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Positive and negative lithographic patterns have been produced in epitaxial layers of GaAs, achieved by electron beam writing and subsequent etching by Cl2 gas at elevated temperatures. A latent image is formed in the native oxide which is either less resistant to thermal Cl2 etching (positive pattern) or more resistant to thermal Cl2 etching (negative pattern), depending on the electron beam dose. The pattern is stable in air for at least several weeks. The tone of the pattern also depends on the electron beam accelerating voltage, the etching conditions, and the thickness and initial state of the native oxide. Significant changes in the resulting lithography are due to changes in an oxide only a few monolayers thick. Both positive and negative patterns can be produced in adjacent areas with high contrast by variation of the electron-beam does. Initial Auger analysis suggests that chemical rearrangement of the native oxide occurs with electron beam exposure. The discovery that the native oxide on GaAs acts as both positive and negative resists opens tremendous possibilities for in situ processing and device fabrication.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103560
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