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  • 1
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the doping incorporation and activation of InP growth using metalorganic chemical vapor deposition on 〈100(approximately-greater-than), 〈311(approximately-greater-than)B, and 〈110(approximately-greater-than) InP substrates. Effects of orientation, growth temperature, and V/III fluxes were studied. The dopants used were Zn from dimethylzinc [(CH3)2Zn] and diethylzinc [(C2H5)2Zn], S from hydrogen sulfide [H2S], Si from silane [SiH4], and Sn from tetraethyltin [(C2H5)4Sn]. The incorporation and activation of the p-type dopant Zn are elevated on the 〈311(approximately-greater-than)B and 〈110(approximately-greater-than) planes, while the incorporation is suppressed for the n-type dopants (S, Si, and Sn). The n-type dopant Sn has similar incorporation and activation on the various substrate orientations studied. Anomalous Zn doping on the higher order planes 〈311(approximately-greater-than)B and 〈110(approximately-greater-than) lead to the Zn incorporation exceeding the solubility limit in InP. Incorporated Zn levels as high as 1.0×1019 cm−3 were measured, and the corresponding activated Zn level was as high as 5.4×1018 cm−3 on a 〈110(approximately-greater-than) InP substrate. Interdiffusion of the p-type dopant Zn into the S-doped n-type InP substrate is inhibited by a high S-doping level and segregates at the substrate–epilayer interface. If the S-doping level is lower than the Zn concentration, then Zn diffuses deep into the substrate at a uniform level.
    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 80 (1996), S. 7094-7103 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High-quality In0.53Ga0.47As epilayers have been grown on semi-insulating (100) Fe-doped InP substrates. The growths were performed by liquid phase epitaxy (LPE) using rare-earth-doped melts in a graphite boat. The rare-earth elements studied were Yb, Gd and Er which act as gettering agents of impurities. Hall measurements show an elevated electron mobility for rare-earth-treated samples over undoped samples, μe=11 470 cm2/V s at 300 K and reduced carrier concentration (n-type), 9.33×1013 cm−3. The Hall results indicate an improvement in layer quality, but suggests that the treated layers are compensated. Photoluminescence (PL) studies show that the layers grown from rare-earth-doped melts have higher integrated PL efficiency with narrower PL linewidths than the undoped melt growths. The grown materials were fully characterized by Fourier transform infrared spectroscopy, double-crystal x-ray diffraction, energy dispersive spectroscopy, secondary-ion-mass spectroscopy, and deep level transient spectroscopy (DLTS). Compositional measurements reveal no measurable incorporation of rare-earth elements into the grown epilayers. DLTS measurements indicate the creation of two deep levels with rare-earth treatment, which is attributed to either the rare earth elements or impurities from within the rare-earth elements. Subsequent glow discharge mass spectrometry measurements reveal many impurities within the rare-earth elements which preferentially might lead to p-type doping centers and/or deep levels. Thus, rare-earth doping of LPE melts clearly improves epitaxial layer quality, however, the purity of commercially available rare-earth elements hinders optimal results. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2191-2193 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Resonant interband tunneling diodes on silicon substrates are demonstrated using a Si/Si0.5Ge0.5/Si heterostructure grown by low temperature molecular beam epitaxy which utilized both a central intrinsic spacer and δ-doped injectors. A low substrate temperature of 370 °C was used during growth to ensure a high level of dopant incorporation. A B δ-doping spike lowered the barrier for holes to populate the quantum well at the valence band discontinuity, and an Sb δ-doping reduces the doping requirement of the n-type bulk Si by producing a deep n+ well. Samples studied from the as-grown wafers showed no evidence of negative differential resistance (NDR). The effect of postgrowth rapid thermal annealing temperature was studied on tunnel diode properties. Samples which underwent heat treatment at 700 and 800 °C for 1 min, in contrast, exhibited NDR behavior. The peak-to-valley current ratio (PVCR) and peak current density of the tunnel diodes were found to depend strongly on δ-doping placement and on the annealing conditions. PVCRs ranging up to 1.54 were measured at a peak current density of 3.2 kA/cm2. © 1998 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 684-686 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Theoretical and experimental studies are presented to understand the initial stages of growth of InGaAs on GaAs. Thermodynamic considerations show that, as strain increases, the free-energy minimum surface of the epilayer is not atomically flat, but three-dimensional in form. Since by altering growth conditions the strained epilayer can be grown near equilibrium or far from equilibrium, the effect of strain on growth modes can be studied. In situ reflection high-energy electron diffraction studies are carried out to study the growth modes and surface lattice spacing before the onset of dislocations. The surface lattice constant does not change abruptly from that of the substrate to that of the epilayer at the critical thickness, but changes monotonically. These observations are consistent with the simple thermodynamic considerations presented.
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 2129-2131 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electro-optic effect and phase modulation in In0.2 Ga0.8 As/GaAs multiple quantum wells have been experimentally studied for the first time. The experiments were done with 1.06 and 1.15 μm photoexcitation which are, respectively, 25 and 115 meV below the electron–heavy hole excitonic resonance. Strong quadratic electro-optic effect was observed near the excitonic edge in addition to the linear effect. These are characterized by r63 =−1.85×10−19 m/V and (R33 −R13 )=2.9×10−19 m2 /V2 . In addition, we observe a dispersion in the value of r63 . The relative phase shifts are higher in the strained system at 1.06 μm than in lattice-matched GaAs/AlGaAs.
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 1125-1127 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The performance characteristics of an AlGaAs dual waveguide vertical coupler with a nonlinear GaAs/AlGaAs multiquantum well coupling medium are demonstrated. The structure was grown by molecular beam epitaxy and fabricated by optical lithography and ion milling. The nonlinear coupling and modulation behavior is identical to that predicted theoretically. The nonlinear index of refraction and critical input power are estimated to be n2=1.67×10−5 cm2/W and Pc=170 W/cm2, respectively. This device also allows reliable measurement of the nonlinear refractive index for varying quantum well and optical excitation parameters.
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 261-263 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This letter reports the successful molecular beam epitaxial growth of high-quality InxGa1−xAs/InxAl1−xAs directly on GaAs. In situ observation of dynamic high-energy electron diffraction oscillations during growth of InxGa1−xAs on GaAs indicates that the average cation migration rates are reduced due to the surface strain. By raising the growth temperature to enhance the migration rate and by using misoriented epitaxy to limit the propagation of threading and screw dislocations, we have grown device-quality In0.15Ga0.85As/In0.15Al0.85As multiquantum wells on GaAs with a 0.5–1.0 μm In0.15Ga0.85As buffer layer. The luminescence efficiency of the bound exciton peak increases with misorientation and its linewidth varies from 11 to 15 meV.
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  • 9
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have examined the effect of growth temperature and growth interruption time on molecular-beam-epitaxial growth of GaAs, Al0.3Ga0.7As, and InxGa1−xAs on GaAs substrates and In0.53Ga0.47As and In0.52Al0.48As on InP substrates using dynamical reflection high-energy electron diffraction as an in situ probe. We have studied the time taken for a rough growth front to recover in the absence of growth as a function of growth temperature for these compounds. It is found that while GaAs and InGaAs surfaces can recover in 15–20 s under ideal growth conditions, Al0.3Ga0.7As surfaces take ≈45 s, and In0.52Al0.48As surfaces take several minutes to recover. Our results also suggest that smoothening of the growth front occurs by rearrangement of the surface atoms, rather than by re-evaporation. We have also studied the effect of strain induced by mismatch on growth modes in the case of InxGa1−xAs on GaAs. Our studies suggest that the presence of strain inhibits the surface migration of adatoms during growth and thus tends to generate a rougher growth front.
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  • 10
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of alloying C with Ge and Si and varying the C/Ge ratio during the growth of very thin layers of the ternary alloy SiGeC grown on Si (100) substrates and the resulting strain modification on self-assembled and self-organized quantum dots are examined. During coherent islanded growth, where dislocations are not formed yet to relieve the strain, higher strain energy produced by greater lattice mismatch acts to reduce the island size, increase the density of islands, and significantly narrow the distribution of island sizes to nearly uniformly sized quantum dots. Strain energy can also control the critical thickness for dislocation generation within the three-dimensional islands, which then limits the maximum height which coherent islands can achieve. After the islands relax by misfit dislocations, the island sizes increase and the island size distribution becomes broader with the increase of misfit and strain. The optimal growth for a high density of uniform coherent islands occurred for the Si0.49Ge0.48C0.03 alloy composition grown on (100) Si, at a growth temperature of 600 °C, with an average thickness of 5 nm, resulting in a narrow size distribution (about 42 nm diameter) and high density (about 2×1010 dots/cm2) of quantum dots. © 1999 American Institute of Physics.
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