ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
  • 1
    Digitale Medien
    Digitale Medien
    On-wafer correlation between total EL2 concentration, shallow acceptor concentration, and Hall properties in semi-insulating GaAs (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 6306-6308 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: By combining infrared absorption measurement of EL2 concentration with conventional measurement of Hall resistivity and mobility, the correlations between the total (neutral plus ionized) EL2 concentration, the net acceptor concentration, and the Hall characteristics across a semi-insulating GaAs wafer have been determined. An increase in the total EL2 concentration is found to be accompanied by a decrease in the resistivity and increase in mobility. Furthermore, there is a positive correlation between the EL2 concentration and the net acceptor concentration.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.345148
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 2
    Digitale Medien
    Digitale Medien
    Origin of current instabilities in GaAs/AlxGa1−xAs heterostructures: Avalanche ionization in the AlxGa1−xAs layer (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 2381-2385 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Pulsed current-voltage measurements on modulation-doped GaAs/AlxGa1−xAs heterostructures are presented at electric fields up to 2 kV/cm. At fields between 0.5 and 2.0 kV/cm we observe up to three well-defined avalanche type current jumps as a function of time. These current jumps show hysteresis effects as a function of the electric field. At even higher electric fields the current becomes irregular and we observe chaotic behavior. To explain the current instabilities we assume that at high electric fields electrons are injected into the AlxGa1−xAs layer parallel to the two-dimensional electron gas. The injected electrons subsequently cause avalanche ionization of occupied DX centers in the AlxGa1−xAs layer. Due to this process, a current filament is created with an exceptionally high mobility which is about 2×104 cm2/V s at 10 K.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.353091
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 3
    Digitale Medien
    Digitale Medien
    Carbon doping and lattice contraction of GaAs films grown by conventional molecular beam epitaxy (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 511-513 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Carbon-doped GaAs films have been grown by solid-source molecular beam epitaxy using a graphite filament. The films were doped from 1×1015 cm−3 to 5×1019 cm−3 and the resulting mobilities are equivalent to beryllium-doped films. A slight dependence of As4/Ga flux ratio on carbon doping was observed. The use of either As2 or As4 did not significantly affect the carbon doping concentrations. Lattice contractions were observed for films doped heavily with carbon or beryllium. For a given doping concentration the contraction is more significant for carbon doping which is consistent with the smaller tetrahedral covalent radius of carbon compared to beryllium. Good agreement between observed and calculated lattice contractions with carbon doping is obtained. Annealing studies on a film doped with carbon at 5×1019 cm−3 indicate that the electrical properties and lattice contraction are quite stable.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.347695
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 4
    Digitale Medien
    Digitale Medien
    Electric field induced parallel conduction in GaAs/AlGaAs heterostructures (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 302-306 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A new mechanism to understand time-dependent features in the conduction of a two-dimensional electron gas (2 DEG) in high electric fields is proposed and discussed. The mechanism is based on the idea that not only the properties of the GaAs/AlGaAs heterostructure have to be included, but also the properties of the transition from the ohmic contact to the heterostructure. We show that the ohmic contact to the heterostructure is fundamentally different from the contact to a bulk semiconductor. In low electric fields electrons cannot move from the contact into the AlGaAs since the conduction band normally lies above the Fermi level. However, when high enough electric fields are applied, the barrier between the contact and AlGaAs is pulled down, allowing conduction in both the AlGaAs and the 2 DEG. We propose a model, in which time-dependent phenomena in the conduction of the 2 DEG can be associated with trapping and detrapping of charge carriers in the AlGaAs. Time-resolved experiments are shown which confirm this hypothesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.347713
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 5
    Digitale Medien
    Digitale Medien
    Si delta-doped In0.15Ga0.85As/GaAs strained quantum well by atmospheric pressure metalorganic chemical vapor deposition (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 276-278 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Si delta-doped In0.15Ga0.85As/GaAs strained quantum wells are demonstrated by atmospheric pressure metalorganic chemical vapor deposition. The samples were characterized by variable temperature Hall effect, high magnetic field magnetoresistance, quantum Hall effect, capacitance-voltage measurements (C-V), and secondary-ion mass spectroscopy. The C-V profile showed a full width at half maximum as narrow as 15 A(ring). Two-dimensional electron gas transport was verified by observing step-like structures in the quantum Hall effect in samples containing sheet densities less than 5×1012 cm−2. Sheet densities as high as 1.0×1013 cm−2 were achieved. C and O contamination were not observed during the Si delta-doping process.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.352128
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 6
    Digitale Medien
    Digitale Medien
    Observation of current filaments in GaAs/AlxGa1−xAs heterostructures using a time-resolved imaging technique (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 3330-3335 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We developed a time-resolved optical beam induced current (TROBIC) technique, and performed time-resolved current imaging experiments on GaAs/AlxGa1−xAs heterostructures under high electric field conditions. These experiments are the first time-resolved imaging experiments of current patterns in a two-dimensional semiconductor structure. We attribute the current patterns observed in the TROBIC images to the formation of current filaments in the AlxGa1−xAs layer, parallel to the two-dimensional electron gas (2DEG). We show that even in samples where the two-dimensional electron gas and the contacts to the 2DEG are perfectly ohmic and homogeneous, current filaments can still develop in high electric fields. These temporal and spatial instabilities in the AlxGa1−xAs layer strongly affect the high-field transport properties of the heterostructure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.350954
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 7
    Digitale Medien
    Digitale Medien
    Photoreflectance characterization of AlGaAs/GaAs modulation-doped heterostructures (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 2355-2360 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Photoreflectance (PR) and reflectance have been applied to characterize undoped and modulation-doped heterostructures of AlGaAs/GaAs grown by metal-organic chemical vapor deposition. The PR spectra were taken on these samples after sequential etching steps in a phosphoric acid etch to study the effects of the surface electric field, the heterointerface, and the two-dimensional electron gas. PR spectra were also taken with an external electric field applied through a transparent gate electrode. The results show that the oscillations appearing near the bandgap energy of GaAs are Franz–Keldysh oscillations originating from the large surface electric field. The surface electric field of the heterostructures can be modified through the application of an external electric field or by etching. The oscillation period is observed to increase with increasing reverse bias or with etching of the GaAs cap layer and the PR features disappear at a forward bias of 0.45 V. The very sharp features associated with the GaAs bandgap energy after etching have also been verified to be Franz–Keldysh oscillations and the presence of a two-dimensional electron gas cannot be confirmed with PR.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.346544
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 8
    Digitale Medien
    Digitale Medien
    Inverted pseudomorphic high electron mobility heterostructures by atmospheric pressure metalorganic chemical vapor deposition (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 71-73 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Inverted pseudomorphic high electron mobility transistor (HEMT) and inverted HEMT heterostructures are demonstrated by atmospheric pressure metalorganic chemical vapor deposition (MOCVD) for the first time and characterized by transmission electron microscopy (TEM), variable temperature Hall effect, and Shubnikov–de Haas measurements. TEM micrographs of both structures show distinct and sharp heterojunction interfaces without indications of interface roughness at the AlGaAs/channel layer interface. Variable temperature Hall effect measurements reveal a monotonic increase in mobility as the temperature is lowered. For the inverted HEMT, the mobility at 15 K is 90 000 cm2/V s with a sheet density of 8.2×1011 cm−2. The mobility of the inverted pseudomorphic HEMT at 15 K is 73 000 cm2/V s with a sheet density of 1.5×1012 cm−2. Shubnikov–de Haas measurements at 4.2 K in magnetic fields up to 18.5 T show clear magnetoresistance oscillations and plateaus in the quantum Hall effect confirming the existence of a two-dimensional electron gas. Fast Fourier power transform of the magnetoresistance versus magnetic field shows two subband levels with a total sheet density of 8.7×1011 cm−2 for the inverted HEMT and a total sheet density of 1.55×1012 cm−2 for the inverted pseudomorphic HEMT in close agreement to the variable temperature Hall effect measurement results.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.104448
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 9
    Digitale Medien
    Digitale Medien
    Combined impurity gettering and defect passivation in polycrystalline silicon solar cells (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 2704-2706 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Polycrystalline silicon wafers have been subjected to annealing (700 °C, 1 h) and to a hydrogen plasma (350 °C, 30 min) during the processing of solar cells. The annealing treatment enhances the bulk minority-carrier recombination lifetime by 19%, presumably by impurity gettering. The plasma treatment improves the lifetime by 26%; hydrogen passivation accounts for at least 2/3 of this improvement. Gettering and passivation are found to be complementary: application of both treatments results in a 43% increase in lifetime compared to standard.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.103805
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 10
    Digitale Medien
    Digitale Medien
    Growth of pseudomorphic high electron mobility heterostructures by atmospheric pressure metalorganic chemical vapor deposition (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 274-276 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Pseudomorphic high electron mobility heterostructures are demonstrated by atmospheric pressure metalorganic chemical vapor deposition for the first time. Transmission electron microscopy (TEM), variable temperature Hall effect measurements, Shubnikov–de Haas measurements, and photoreflectance were applied to characterize the heterostructures. TEM micrographs of the cross section reveal sharp heterojunction interfaces. Variable temperature Hall effect measurements show a monotonic increase in mobility as the temperature is lowered. With a spacer thickness of 120 A(ring), a peak mobility of 80 000 cm2/V s at 20 K and a sheet carrier concentration of 1.05×1012 cm−2 are obtained. Similarly, a thinner spacer (60 A(ring)) shows a peak mobility of 57 000 cm2/V s at 25 K with a sheet carrier concentration of 1.40×1012 cm−2. Shubnikov–de Haas measurements in magnetic fields up to 18.5 T show clear oscillations and the quantum Hall effect confirming the existence of a two-dimensional electron gas.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.102806
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...