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  • 1
    Electronic Resource
    Electronic Resource
    Surface recombination current and emitter compositional grading in Npn and Pnp GaAs/AlxGa1−xAs heterojunction bipolar transistors (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 641-643 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An experimental study of current gain in Npn and Pnp GaAs/AlxGa1−xAs heterojunction bipolar transistors (HBTs) with either compositionally graded or abrupt base-emitter heterojunctions is reported. In both Npn and Pnp device structures, linear compositional grading increases the amount of base current and lowers the transistor current gain from that observed in devices with abrupt base-emitter heterojunctions. Analysis of the dependence of the base current on emitter mesa size indicates that surface recombination dominates the Npn and Pnp base current in both the abrupt and graded devices. Taken together, these results suggest that the magnitude of the surface recombination current in Npn and Pnp GaAs/AlxGa1−xAs HBTs depends not only on the surface recombination velocity of the GaAs base free surface, but also on the energy barrier presented by the emitter to minority carriers attempting to enter the surface channel at the emitter mesa surface. Linear compositional grading of the emitter results in a lowering of this barrier and an increase in base current associated with carrier injection to the transistor surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100904
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of rapid thermal annealing temperature on the electrical properties of Be-implanted GaAs p-n junctions (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 2244-2246 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Planar, Be-implanted p-n junctions were fabricated in GaAs with rapid thermal annealing (RTA). Five second isochronal anneals over a temperature range of 600–1000 °C were studied with secondary ion mass spectrometry (SIMS), sheet resistance measurements, and variable diameter p-n junctions. Sheet resistance measurements indicate that a minimum RTA temperature of 600 °C is necessary for electrical activation of the implanted Be. SIMS analysis indicates that significant outdiffusion and surface evaporation of Be occur at all RTA temperatures in this range, while indiffusion of Be is insignificant for concentrations below 1×1018 cm−3. Forward bias current in diodes ranging in diameter from 10 to 1000 μm is dominated by surface recombination, rather than bulk space-charge recombination, over the entire 600–1000 °C temperature range. The magnitude of the surface recombination current is insensitive to the RTA temperature, which suggests that 600 °C RTA should be sufficient for the formation of satisfactory p-n junctions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99544
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Growth and diffusion of abrupt zinc profiles in gallium arsenide and heterojunction bipolar transistor structures grown by organometallic vapor phase epitaxy (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 4485-4493 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The growth and diffusion of abrupt Zn profiles in undoped gallium arsenide (GaAs), silicon-doped GaAs, and heterojunction bipolar transistor structures grown by organometallic vapor phase epitaxy have been studied using secondary ion mass spectrometry depth profiling. The depth profiles indicate that abrupt (within 100 A(ring)) turn-on of Zn doping to levels approaching 1020 cm−3 are obtainable, while abrupt turn-off is limited to about two orders of magnitude due to dopant tailing toward the surface resulting from residual Zn in the reactor. The sharp diffusion fronts resulting from post-growth anneals indicate that the Zn diffusion coefficient has a concentration dependence. However, the diffusion of Zn at high concentrations appears to be inhibited by crystal defect kinetics resulting in a relatively concentration-independent Zn diffusion coefficient. The V/III growth ratio did not have an effect on Zn diffusion in undoped or silicon-doped GaAs. The diffusion of Zn in heterojunction bipolar transistor structures differs in that the diffusion of Zn into the GaAs collector is larger by an order of magnitude and decreases with an increase in V/III growth ratio. In addition, the diffusion of Zn into the aluminum gallium arsenide (AlGaAs) emitter is significantly lower and more effectively inhibited by an increase in V/III ratio than the diffusion of Zn into the GaAs collector.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.340143
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Observation of radiative and nonradiative tunneling in GaAs/AlxGa1−xAs heterojunction bipolar transistors with compositionally graded base-emitter heterojunctions (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 3282-3285 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A comparative experimental study of 77-K current gain and electroluminescent (EL) spectra in Npn GaAs/AlxGa1−xAs heterojunction bipolar transistors (HBTs) with either compositionally graded or abrupt base-emitter heterojunctions is reported. Shifting-peak spectra associated with radiative tunneling of carriers into the base-emitter heterojunction space-charge region are observed to dominate the 77-K EL spectra of HBTs with linearly graded emitters. The 77-K EL spectra of the abrupt HBTs are characterized by a peak whose energy position is invariant with respect to base-emitter bias and corresponds to recombination of electrons diffusing across the HBT base. Comparison of EL peak intensity and transistor base current indicates that the graded HBT current gain at 77 K is determined by nonradiative tunneling of electrons and holes to deep levels at the base-emitter junction. The loss of minority carriers to radiative and nonradiative tunneling current mechanisms in the graded HBT causes the 77-K current gain of the graded HBT to be significantly lower than that of the abrupt HBT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342687
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  • 5
    Electronic Resource
    Electronic Resource
    Ideal electronic properties of a p-Ge/p-Al0.85Ga0.15As interface (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 318-320 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The isotype p+-Ge/p-Al0.85Ga0.15As interface is examined in this study. It is shown that a lattice-matched epitaxial layer of p-Al0.85Ga0.15 on p+-Ge acts like a minority-carrier mirror. Evidence for this action comes from improved short-wavelength response of a p+-n Ge solar cell and from a tenfold reduction in the dark saturation current of a p+-n Ge junction. At the same time, the p+-Ge/p-Al0.85Ga0.15As interface is electrically transparent to majority-carrier hole transport. Similarity of measured specific resistivities of Ti/Au ohmic contacts directly to Ge and through a p-Al0.85Ga0.15As layer to p+ Ge leads to this conclusion in spite of about 1 eV valence-band offset at the Ge-Al0.85Ga0.15As heterojunction interface. A possible mechanism for the hole transport through such an interface is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106378
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  • 6
    Electronic Resource
    Electronic Resource
    Visible light emission from quantized planar Ge structures (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 1603-1605 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Visible photoluminescence has been observed near 1.9 eV at 300 K from quantized planar Ge structures. This is the first observation of luminescence in Ge and is similar to the recently reported luminescence from porous Si. The quantum structures are prepared from bulk Ge substrates, and both n- and p-type Ge produce luminescence at room temperature. These structures are fabricated by plasma-assisted etching using a CF4/O2 gas mixture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106269
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Photoluminescence of porous silicon buried underneath epitaxial GaP (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 889-891 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Recent observations of visible, room-temperature photoluminescence in porous Si have stimulated research aimed at the realization of efficient, Si-based electroluminescent devices. To achieve electroluminescence, it may be beneficial to generate carriers with sufficient energy to populate the states of the quantum-confined Si structures. A viable method to accomplish this is to utilize a wide-band-gap heterojunction injector, such as GaP. Toward that end, we report the successful formation of porous Si buried underneath GaP islands, and we demonstrate that the buried porous Si layer exhibits strong photoluminescence (λ≈7000 A(ring)).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106495
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    Paper (German National Licenses)
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