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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 7615-7617 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Porous Si (PS) layers are prepared by stain etching in a HF/NaNO2 solution on both p- and n-type crystal Si substrates, and are characterized by photoluminescence (PL), electron paramagnetic resonance (EPR), and infrared absorption (IR) spectroscopy. The PL spectra under 488 nm laser excitation exhibit a strong peak at 680–720 nm for various samples of different substrate parameters and remain stable upon aging in air or γ irradiation; as-etched (∼20 min in air before measurement) and aged (for up to six months) samples show no detectable EPR signal but the γ-irradiated samples show an isotropic g=2.006 signal of peak-to-peak linewidth of 1.1 mT supporting an amorphous Si structure; the IR spectra show both hydrogen and oxygen related IR modes in the as-etched samples and the former decreases with aging time in air while the latter increases. Comparing our results with those of anodically etched PS samples we conclude that: (1) the PL peak position of the stain PS seems to be unique and stable as compared with that of the anodic PS varying in 620–830 nm; (2) the isotropic EPR signal of the stain PS reflects no crystallinity, in contrast with the anisotropic signal of the anodic PS; and (3) obvious oxidation in the as-etched stain PS is also in contrast with the nonobservation of oxygen-related IR modes in the as-etched anodic PS. We discuss the results in terms of structural properties and PL mechanism of PS.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 536-538 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Having been exposed to hydrogen plasma, Te-doped GaAs wafers were deposited with metal Ti, to form Ti/n-GaAs Schottky barrier diodes (SBD). It was found that due to hydrogenation the Schottky barrier height (SBH) of the SBD decreases from 0.76 to 0.58 eV and the effective Richardson constant A** decreases from 11 to 0.03 A/cm2/K2. Annealing the hydrogenated SBD at different reverse biases at 100 °C produces SBHs that have a one-to-one correlation with the biases of reverse-bias annealing (RBA), i.e., the SBH can be controlled, within the range 0.58–0.74 eV, by the bias of RBA. When the reverse bias is equal to or larger than 3 V, the SBH and the effective Richardson constant of the hydrogenated SBDs after RBA are very near to those of SBDs without hydrogenation. This means that a RBA with a bias higher than a critical value, 3 V in our case, can remove the effects of hydrogenation, but if the SBD is annealed again without a bias at 100 °C for 1 h or more, its SBH and effective Richardson constant recover their hydrogenated values. The main experimental facts can be explained qualitatively by a simple theoretical model.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 5751-5753 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Neutron diffraction has been used to study the magnetic fluctuations and long range order of the Dy ions in single crystals of superconducting DyBa2Cu3O7. The temperature dependence of the rod of scattering, characteristic of 2D behavior, has been measured above and below the 3D Néel temperature (TN (approximately-equal-to) 0.9 K). This rod intensity is observed to increase as the temperature decreases until TN is reached, and then the intensity decreases rapidly below TN. The 2D magnetic correlation length, which is obtained from measurements of the width of the rod, grows continuously with decreasing temperature, then reaches a resolution-limited maximum at the Néel temperature when long range magnetic order sets in. At low T, two separate types of simple 3D antiferromagnetic structures are found, one characterized by a wave vector of (1/2 1/2 0), and the other by (1/2 1/2 1/2). We believe the two types of order occur because the (dipolar) energies for these two configurations are nearly identical. This behavior is analogous to the 2D and 3D magnetic order of Er observed in ErBa2Cu3O7.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 4395-4399 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Donor related states in Si-doped AlGaAs with Al compositions ranging from 0.30 to 0.59 were investigated by capacitance measurements. In addition to the stable Si-DX state, two metastable states of the silicon donor were observed. Of the two metastable states, the shallower one is attributed to the X-conduction band related effective mass state arising from substitutional silicon on the group III site. The deeper one is proposed to be related to a donor configuration different from both the substitutional configuration and that of the DX state. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 3493-3503 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Deep level transient spectroscopy (DLTS) and single shot capacitance techniques were used to investigate Si doped AlxGa1−xAs with Al compositions ranging from 0.30 to 0.59. Under illumination, an additional DLTS peak was observed in samples with Al compositions close to x=0.38. This peak has been shown to originate from a localized state with an energy level shallower than the DX ground state and energy barriers for both electron emission and capture processes. Persistent photoconductivity effects related to this state were observed below 50 K. Evidence is provided that this state is a metastable state of the Si donor. Its origin is discussed in terms of the intermediate state of a negative U DX center and a metastable negative U configuration of the Si donor. A further photoinduced DLTS peak was observed within a narrow Al composition range that has been identified as the shallowest DX level of the four distinct DX levels originating from different local environments of the donors. © 1996 American Institute of Physics.
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 2860-2865 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Uniformly Si doped GaAs/Al0.33Ga0.67As multilayer structures have been studied by deep level transient spectroscopy (DLTS) and photocapacitance measurements. DLTS spectra showed five peaks which are related to defects in the GaAs layers. The concentration of these defects decreased with increasing layer thickness. An additional peak, which has been observed with forward bias filling pulses, is suggested to be related to defects near the surface, most probably due to defect accumulation in multilayers. Their emission and capture properties as well as photoionization cross sections have been studied. Evidence is provided that the emission and filling processes of these deep levels are modified due to the energy quantization in the conduction band and the carrier transport through the quantum structures. No DX center related DLTS peaks or other features like persistent photoconductivity effects have been observed in any of our samples. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 5592-5594 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Au/n-Si Schottky barrier (SB) which contains hydrogen has a 0.10 eV lower SB height (SBH) than that without hydrogen. For the hydrogen-containing SB, zero bias annealing (ZBA) decreases the SBH while reverse bias annealing (RBA) increases it. In addition, ZBA and RBA cycling experiments have been made which reveal a reversible change of the SBH within at least four cycles. The annealing temperature of ZBA and especially of RBA influences the SBH. We interpret the above effect in terms of an interaction between hydrogen and metal-semiconductor interface states.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 859-863 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Acceptorlike states with energy levels in the lower part of the band gap have been observed by photocapacitance measurements in Si-doped molecular-beam-epitaxial-grown AlxGa1−xAs (x=0.30–0.59). The microscopic structure of these defects is still unclear. Their concentration, however, can exceed the net donor concentration. The energy positions of the acceptorlike states as well as their photoionization cross sections of holes and electrons have been studied for different x. Due to their large concentration, these states may disturb experiments performed on DX centers which are often assumed to be the main electronic levels in these materials. © 1996 American Institute of Physics.
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  • 9
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pseudo-Hall effect (PHE) in Ni thin-film squares of 1–5 μm size is measured with a constant current through two leads along one diagonal of the square and the voltage output from leads along the other diagonal. The PHE voltage in response to an in-plane magnetic field depends on the square size and field orientation. The minimum PHE voltage at low field is close to zero only with the 2 μm square containing four symmetrical closure domains leading to a 600% relative change in PHE voltage. The PHE signal is found the largest when the field direction is along the square side while the smallest when along the square diagonal. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 4261-4263 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ti/n-GaAs Schottky barrier diodes were prepared on nitrogen-implanted n GaAs. The Schottky barrier height of the diodes was found to be 0.96 eV, 0.12 eV higher than that of the samples without N implantation. Four distinctive electron traps E1(0.111), E2(0.234), E3(0.415), and E4(0.669) and one hole trap, H(0.545), have been observed with deep level transient spectroscopy. Defect models of these deep levels are proposed and the role of H(0.545) in the Schottky barrier formation is also discussed. © 1995 American Institute of Physics.
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