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  • 1
    Electronic Resource
    Electronic Resource
    Spin-dependent confinement in DMS-based heterostructures (invited) : 38th Annual Confrerence on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 5714-5718 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe the results of a magneto-optical study of a class of semiconductor heterostructures in which one of the constituent layers is a diluted magnetic semiconductor (DMS). The large magnetic band splittings of DMS materials result in spin-dependent confining potentials for electrons and holes which can be changed externally by varying the applied magnetic field. The modifications in the band alignment result in changes, sometimes dramatic, of the optical properties in the vicinity of the band gap.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355593
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  • 2
    Electronic Resource
    Electronic Resource
    Coexistence of Brillouin and Van Vleck spin exchange in Zn1−xMnxSe/Zn1−yFeySe spin superlattice structures : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 5725-5727 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied a new type of semiconductor quantum well system in which the carrier-ion exchange interactions are determined by the spin of the carrier. The samples consist of alternating layers of Zn1−xMnxSe and Zn1−yFeySe grown by molecular-beam epitaxy (MBE). At zero field, the carriers initially interact randomly with both transition metal species. When a magnetic field is applied, the excitonic wave functions are increasingly localized in one or the other of the magnetic layers according to their spin state as the competing spin exchange interactions define the confining potential. The spin components of the heavy hole exciton are subsequently dominated by different exchange interactions as revealed by their temperature and field dependence: the behavior of the spin-down component (−3/2,−1/2) is described by exchange interactions of the carriers with the Mn2+ ions and exhibits Brillouin paramagnetic behavior, while the spin-up component (+3/2,+1/2) is dominated by interactions with Fe2+ ions and exhibits Van Vleck paramagnetism. These structures are thus characterized by an initial competition and eventual coexistence of Brillouin- and Van Vleck-like paramagnetic behavior for the exciton.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355595
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  • 3
    Electronic Resource
    Electronic Resource
    Optical study of an n-type modulation-doped GaAs/AlAs multiple quantum well structure (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2100-2102 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present an optical study (photoluminescence and Raman scattering) of a GaAs/AlAs multiple quantum well structure doped n-type in the AlAs barriers. The photoluminescence shows that the Si donors of the barriers release their electrons in the GaAs wells, creating a dense quasi-two-dimensional electron gas. The Raman spectra contain a feature associated with the e1→e2 intersubband transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354730
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  • 4
    Electronic Resource
    Electronic Resource
    Spin lifetimes in diluted magnetic semiconductor spin superlattices : 37th Annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 6051-6053 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The growth of spin superlattice structures in which spin-up and spin-down carriers occupy alternating layers in the structure has recently been reported. We report here measurements of electron and hole spin lifetimes and spin relaxation processes. In dc photoluminescence spectra, both the higher-energy (+1/2,+3/2) and lower-energy (−1/2,−3/2) heavy-hole exciton interband transitions are observed, even though it would be energetically favorable for the spin-up carriers to first relax to the spin-down state before radiative recombination. From the field dependence of the intensity ratios of these components and a rate equation model, we determine the heavy hole τhs and electron τes spin lifetimes relative to the radiative lifetime τr, with τhs/τr≈4.5 and τes/τr≈0.08, so that the heavy-hole spin lifetime is ≈50 times longer than that of the electron. This is attributed to the strain-induced splitting of the heavy- and light-hole bands, which prevents fast spin relaxation of the holes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353466
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  • 5
    Electronic Resource
    Electronic Resource
    Properties of low-pressure chemical vapor epitaxial GaN films grown using hydrazoic acid (HN3) (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 2197-2207 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have grown high-quality GaN films on sapphire using a new nitrogen precursor, hydrazoic acid (HN3). Films were grown at 600 °C on (0001) sapphire substrates in a low-pressure chemical-vapor-deposition system using triethylgallium and hydrazoic acid as precursors. Subsequently, we have conducted a complete study of the surface, structural, electrical, and optical properties of these GaN films, and our early results are very encouraging. All films were of wurtzite crystal structure, slightly polycrystalline, and n type at about 2×1017 cm−3. We find the films to be efficient light emitters in the near-band edge region of the spectrum. Analysis of the emission energies and kinetics suggests that the midgap emission results from a superimposed deep-donor-to-shallow-acceptor emission and a deep-donor-to-valence-band emission, where the deep donor consists of a distribution of energy levels, thereby yielding a broad emission band. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364253
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  • 6
    Electronic Resource
    Electronic Resource
    Faraday rotation from Zn1−xFexSe epilayers (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 583-585 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present Faraday rotation measurements on Zn1−xFexSe films grown by molecular beam epitaxy. The samples exhibit giant Faraday rotation characteristic of diluted magnetic semiconductors. Measurements were carried out at T=4.2 K and in magnetic fields up to 8 T. The Faraday rotation angle shows a strong resonance for photon energies close to the band gap. The resonance curves were fitted by a simple dielectric model using the exciton oscillator strength as a fitting parameter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106617
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  • 7
    Electronic Resource
    Electronic Resource
    Optical properties of GaN epitaxial films grown by low-pressure chemical vapor epitaxy using a new nitrogen source: Hydrazoic acid (HN3) (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 2433-2435 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report results of our growth and characterization of GaN films using low-pressure chemical vapor epitaxy with a new nitrogen source, hydrazoic acid (HN3). This growth technique allows for low-temperature deposition, low III/V ratios, and increased deposition rates (up to ∼2–3 μm/h). The deposited films show Ga:N atomic ratios of 1±0.25 based on our x-ray photoelectron spectroscopy analyses, and the He(II) UPS (ultraviolet photoelectron spectroscopy) spectra compare favorably with the semi-ab initio calculations for the GaN valence bands and with the reported UPS data for single crystal GaN films. X-ray and Raman spectra show deposited films crystallized in the expected wurtzite structure. We find these epitaxial films to be efficient light emitters in the blue or yellow region of the spectrum, depending upon growth conditions. Our photoluminescence time-decay kinetics confirm the excitonic nature of the blue emission. Lastly, far infrared time-domain spectroscopy shows the low carrier concentration of this material. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113964
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