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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2630-2632 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaN-rich side of GaNP and GaNAs layers is grown at 750 °C by gas-source molecular beam epitaxy. Phase separation is observed for the layers with P and As composition of over 1.5% and 1%, respectively. Photoluminescence (PL) spectra for the non-phase-separated GaNP (P composition: 0.37%) and GaNAs (As composition: 0.26%) show redshift of 50 and 40 meV, respectively, from that of GaN, and exhibit Stokes shift of about 80 meV which is smaller than that of GaN (100 meV). On the other hand, the PL spectrum for the phase-separated GaNP shows a large redshift peaking at 2.101 eV. This peak is considered to be an emission from the phase-separated GaP-rich GaPN region. PL excitation spectrum shows two large broad peaks. One at 2.982 eV corresponds to the absorption at the Γ point of GaP-rich region, and the other at 2.308 eV corresponds to the absorption at the isoelectronic band edge of GaP-rich GaPN alloy originated from the X point of GaP. In the case of phase-separated GaNAs, no PL is observed, suggesting that the optical properties are much more sensitive to crystalline quality in GaAs-rich GaAsN than in GaP-rich GaPN. © 1998 American Institute of Physics.
    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 74 (1993), S. 2300-2305 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Radiation damage and its recovery process of molecular-beam epitaxy grown AlSb implanted with Ga ions is studied using Raman scattering for Ga ion fluences ranging from 1×1013 to 5×1014 cm−2 and for annealing temperatures ranging from 300 to 600 °C. With increasing fluences the AlSb longitudinal optical (LO) phonon mode shifts to lower frequency and exhibits an asymmetric broadening. Recovery of radiation damages in the ion implanted AlSb is observed after annealing at as low as 300 °C. On the other hand, after annealing at above 500 °C, disordering of the crystalline structure due to the outdiffusion of Sb is observed. The damage states and the recovering behaviors are quantitatively estimated using the spatial correlation model on the LO mode.
    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 73 (1993), S. 1161-1167 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: MOMBE (metalorganic molecular beam epitaxy) growth characteristics of Sb containing ternary alloys, InGaSb, and GaAsSb are investigated. In the growth of InGaSb using TEGa (triethylgallium), TMIn (trimethylindium), and Sb4 (elemental antimony), the enhanced desorption of methyl-In molecules at a substrate temperature Tsub of around 500 °C as well as the enhanced desorption of ethyl-Ga molecules at around 515 °C are observed. They are due to the weak bond strength of antimonide compounds. Furthermore, the decrease of Ga solid composition with increasing Sb4 flux and the increase of GaSb partial growth rate with TMIn flow rate are also observed at as high as 500 °C. This is caused by the fact that the site blocking effect of excess Sb atoms exists up to higher Tsub. In the growth of GaAsSb using TEGa, TEAs (triethylarsine), and TESb (triethylstibine), the Sb composition versus TESb/(TEAs+TESb) curve exhibits a bowing characteristic, which is similar to that in the MOVPE (metalorganic vapor phase epitaxy) growth and is different from that in the MBE (molecular beam epitaxy) growth. Mass transport properties of Sb molecules in the MOMBE are considered to be similar to that in the MOVPE. It is found that the Tsub dependence of Sb composition is much weaker than that in the MBE, which is a superior point of MOMBE in the growth of antimonide alloys.
    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 77 (1995), S. 1952-1958 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Metalorganic molecular beam epitaxy (MOMBE) growth characteristics of GaAs using triethylgallium (TEGa) and trisdimethylaminoarsenic (TDMAAs) are studied in detail by using reflection high energy electron diffraction intensity oscillations. It is found that the GaAs growth rate variation with substrate temperature (Tsub) is similar to that in the MOMBE growth of GaAs with TEGa and elemental As (As4) except in the high Tsub region, despite the use of uncracked TDMAAs instead of As4. GaAs growth starts at about 350 °C and shows a maximum growth rate at about 500 °C. However, the absolute growth rate is about 15% lower than that using As4 with the same TEGa flow rate in the mass-transport limited growth region. Above 600 °C the growth rate shows a rapid decrease with increasing Tsub. Further, it is found that etching of GaAs occurs when only TDMAAs is supplied to the GaAs surface at Tsub above 500 °C. Unintentionally doped GaAs films show n-type conduction in the whole Tsub range investigated with the highest 77 K electron mobility of 22 000 cm2/V s and a low carrier concentration of 2×1015 cm−3 for the 650 °C grown samples. 4.2 K photoluminescence spectra show an exciton-bound-to-impurity emission peak at the wavelength of 819.3 nm with a full width at half-maximum of less than 3.5 meV indicating good optical qualities. © 1995 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 74 (1993), S. 579-585 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Recovery process in GaSb crystals with Ga ion implantation and subsequent annealing by rapid thermal annealing (RTA) or furnace annealing (FA) methods are studied by Raman scattering. The intensity of the GaSb LO phonon mode decreases with increasing ion implantation fluence. It is found that the threshold fluence to the amorphization for the Ga ion implanted GaSb is 5×1013 cm−2. It is much lower than that for InP (1×1014 cm−2). In the face-to-face FA, the recovery processes in the Ga ion implanted GaSb are very different above and below the fluence of 5×1014 cm−2. For the 5×1014 cm−2 Ga ion implantation, no recovery is observed. Below 5×1014 cm−2 implantation, the GaSb LO mode intensity increases with increasing annealing temperature and with time up to 400 °C and 15 min, respectively. However, the recovery of damage is very poor compared with that of GaAs, InP, and GaP. On the other hand, in the Si3N4 caped RTA the recovery is observed even for the 5×1014 cm−2 implantation. New modes are observed at around 114 and 150 cm−1 in the implanted and annealed GaSb samples. These two modes are related to Eg and A1g modes of Sb—Sb bond vibrations, respectively, and are produced due to the outdiffusion of Sb atoms. It is found that the face-to-face annealing enhances the outdiffusion of Sb, and that the Si3N4 caped RTA process is superior to the face-to-face FA process for the healing of the damaged layers. These anomalous behaviors are closely related to the weak bond strength of Sb containing materials. The degree of the recovery as a function of annealing temperature, annealing time, and ion implantation fluence is also investigated in both RTA and FA methods.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 479-483 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Refractive indices of InGaAs/InAlAs multiquantum-well layers grown by molecular-beam epitaxy are determined by reflectance measurements as a function of photon energy and barrier width, i.e., average Al content. These results are well explained by the single-oscillator model; oscillator energy (E0) and dispersion energy (Ed) values vary linearly with average Al content. These values are, however, found to differ from the values obtained by the linear approximation of the parameters for binary alloys. Discussion of this discrepancy is also presented.
    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 59 (1986), S. 3489-3494 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The properties of a deep electron trapping center found in Si-doped In0.51Ga0.49−xAlxP (x=0.24) grown on Si-doped GaAs(100) substrates using molecular-beam epitaxy are studied. The trapping parameters for this center are determined as follows: thermal activation energy 0.48 eV, photoionization energy 1.25 eV, and capture barrier 0.10 eV. The concentration of this center is about seven times as high as that of the shallow donor state and is found to increase with an increasing amount of Si atoms incorporated into the crystal. The thermally activated persistent behaviors of photocarriers are also observed at low temperatures. These results suggest that this center can be regarded as a kind of DX center originally found in AlGaAs, which should be depicted as a state with large lattice relaxation using a configuration coordinate diagram.
    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 63 (1988), S. 1955-1960 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Deep electron-trapping centers present in InAlAs (barrier layers) are found to have significant effects on the optoelectronic properties of InGaAs/InAlAs multiquantum-well structures grown by molecular-beam epitaxy. When the energy depths of these centers are less than the discontinuity of the conduction band for this heterojunction, they come to be ionized to produce two-dimensional electron gas in the quantum well (InGaAs). The excess electrons thus accumulated dissociate the excitons by screening the attractive potential between electrons and holes. Hence, the deep levels in barrier layers must be reduced in order to improve the optoelectronic quality of this class of multiquantum-well structures.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 1073-1078 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoelectric fatigue and spike photoconductivity (SPC) are systematically studied in twenty-three pieces of undoped semi-insulating liquid-encapsulated Czochralski GaAs crystal (six ingots, four suppliers). Distributions among samples for photosensitivity, SPC-decay time constant, SPC spectrum, and oscillatory behavior are discussed. Through these studies, the metastable state X* (some kind of excited state of the main deep center X present in GaAs) is found to be classified into two states X@B|a and X*f , according to whether the electronic transition X*→X due to irradiation with the photon energy near 0.80 eV is allowed or forbidden, respectively. State X@B|a is responsible for the SPC phenomenon, while both states X*a and X@B|f are responsible for photoelectric fatigue. Moreover, the concentration of state X*a is estimated to be about 10−3 times that of state X*. These results suggest that there exist various configurations of metastable states.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 2849-2851 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polycrystalline GaN layers were grown on W, Mo, Ta, and Nb metal substrates by gas-source molecular-beam epitaxy using an ion-removal, electron-cyclotron-resonance radical cell. X-ray diffraction rocking curves showed preferential GaN(0002) or GaN(10–11) orientations. The grain sizes ranged from 100 to 800 nm. Strong photoluminescence (PL) emission without yellow luminescence was observed from these polycrystalline GaN layers. At 77 K, PL peaks at 3.46 and 3.26 eV were observed, and their temperature dependence fit a simple relation based on the number of phonons. The higher-energy peak probably was due to the free excitonic transition in hexagonal GaN. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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