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  • 1
    Digitale Medien
    Digitale Medien
    Optical waveguides formed by deuterium passivation of acceptors in Si doped p-type GaAs epilayers (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 4151-4155 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We report on the use of plasma hydrogenation of Si doped, p-type GaAs crystalline samples to form infrared waveguides through acceptor passivation. Epilayers grown by liquid phase epitaxy were exposed to a deuterium plasma for ninety minutes at three different temperatures. Secondary-ion mass spectrometry (SIMS) analysis indicated that the deuterium concentrations in the crystals after plasma exposure were nearly equal to the acceptor level and extended to depths between 2.0 and 4.0 μm. Reflectivity measurements showed that the epilayers had passivated regions whose thicknesses corresponded to those determined by SIMS analysis. Laser coupling experiments at 1.15 μm showed optical waveguiding in each sample and lowest propagation losses were on the order of 35 dB/cm. At a wavelength of 1.523 μm, only the sample processed at the highest temperature exhibited laser guiding and losses were considerably higher.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.350849
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  • 2
    Digitale Medien
    Digitale Medien
    Characterization of hydrogenated GaAs/AlGaAs multiple quantum well structures (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 8489-8494 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We report on the photoluminescence properties and the hydrogen depth distributions of plasma treated GaAs/AlGaAs multiple quantum well (MQW) structures. Specimens grown by molecular beam epitaxy were exposed to a deuterium plasma under different temperature-time conditions. Photoluminescence measurements were made at 4.2 K, using low and high excitation powers, on the hydrogenated samples and on untreated partners. A decrease in the linewidth of the free exciton and an increase in the peak intensity were observed in specimens following plasma treatment. In general, each of the hydrogenated MQW specimens displayed an increase in luminescence efficiency and a diminution of impurity-related peaks after hydrogenation. Secondary ion mass spectrometry measurements yielded depth distributions for 2H and Al atoms. In samples having the best luminescence, the 2H was nearly constant throughout the MQW region, at about 1018 cm−3.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.353401
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  • 3
    Digitale Medien
    Digitale Medien
    Proton, deuteron, and helium implantation into GaAs and LiNbO3 for waveguide fabrication (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 5006-5010 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Hydrogen and helium implantation into GaAs, LiNbO3, and other crystals has been shown to produce planar or channel waveguides via defects/damage and/or carrier removal or compensation. We have measured implanted depth distributions of 1H, 2H, and 4He in GaAs and LiNbO3 as functions of ion energy, ion fluence, substrate temperature, and annealing temperature using secondary ion mass spectrometry. We have studied the defect depth distribution for hydrogen-implanted GaAs by transmission electron microscopy. We have determined the lateral spread of 1H and 2H ions implanted into GaAs by varying the angle of implantation; this relates to the increase in width of closely spaced parallel channel waveguides made using patterned masks.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.335275
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  • 4
    Digitale Medien
    Digitale Medien
    Correlation of substitutional hydrogen to refractive index profiles in annealed proton-exchanged Z- and X-cut LiNbO3 (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 2697-2708 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Previous disagreements concerning a linear correlation between the hydrogen (H) concentration and the extraordinary refractive index ne in proton-exchanged lithium niobate (LiNbO3) have been resolved by partitioning the total H into optically active substitutional H and optically inactive interstitial H. The H and Li spatial variations in both Z- and X-cut crystals were determined by secondary-ion-mass spectrometry (SIMS) with a quantitative evaluation in atoms/cm3. These samples were proton exchanged in neat benzoic acid at 185 °C and then were annealed at 400 °C for times t from 6 to 240 min in wet flowing oxygen. For the Z-cut crystals, fit of the SIMS measured H profiles by expressions obtained from the diffusion equation for diffusion from a finite layer gave a substitutional H diffusivity of DZs=5.0±0.3×10−12 cm2/s and an interstitial H diffusivity of DZi=1.4±0.1×10−11 cm2/s. The wet flowing oxygen acts as a constant source of interstitial H at the surface with the diffusivity DZi and gives an integrated H concentration due to the flowing wet oxygen which increases as (square root of)t. The Li diffusivity was DLiZ=4.8±0.2×10−12 cm2/s which is nearly equal to DZs. For X-cut crystals, the substitutional H diffusivity was DXs=3.4±0.2×10−12 cm2/s and the interstitial diffusivity was DXi=1.3±0.2×10−11 cm2/s. The ne profiles were evaluated by means of optical prism-coupling measurements and numerical simulations. In both cases of crystal orientation, the effective index diffusivity is nearly equal to the diffusivity of substitutional H. Furthermore, there is an excellent linear relationship between the ne profile and the corresponding substitutional H distribution. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.358738
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  • 5
    Digitale Medien
    Digitale Medien
    Thermal stability of hydrogen in LiAlO2 and LiGaO2 (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 3848-3850 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Hydrogen as 2H has been incorporated into LiAlO2 and LiGaO2 by both ion implantation and by exposure to a plasma at 250 °C. In the implanted samples, approximately 50% of the hydrogen is lost from the surface during annealing at 500 °C for 20 min, and essentially all is gone by 700 °C. This hydrogen retention is considerably less than for other materials that are being used as substrates for III-nitride epilayer growth, such as SiC and sapphire. The indiffusion of 2H from a plasma is much faster for LiAlO2 with an apparent diffusivity at 250 °C of ∼10−13 cm−2 s−1, approximately two orders of magnitude larger than for LiGaO2. Hydrogen outdiffusion from LiAlO2 or LiGaO2 substrates during III-nitride epitaxy should not be a significant problem; the hydrogen should have left these materials at temperatures less than epitaxial layer growth temperatures. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.117125
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  • 6
    Digitale Medien
    Digitale Medien
    Redistribution of H and Be in GaAs/AlAs multilayer structures with post-implantation annealing (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 1968-1971 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The redistribution of implanted atoms within GaAs/AlAs multilayer structures due to post-implantation furnace annealing is reported. The structures were grown using molecular-beam epitaxy on GaAs substrates and implanted with either hydrogen or beryllium ions. After furnace annealing at temperatures up to 700 °C, these samples were examined using secondary ion mass spectrometry. The measurements show that the hydrogen and the beryllium atoms redistribute with post-implantation annealing and that both species accumulate at the buffer layer-substrate interface. The concentration of atoms at this interface can exceed 1×1019 cm−3 and may be related to the crystal imperfections created during the inital stages of epitaxy. The significant redistribution of implanted ions may also alter the optoelectronics properties of multilayer semiconductor structures processed in this manner.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.342886
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  • 7
    Digitale Medien
    Digitale Medien
    Electrical effects of atomic hydrogen incorporation in GaAs-on-Si (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 347-353 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have introduced atomic hydrogen by two methods into GaAs layers epitaxially grown on Si substrates, namely, by exposure to a hydrogen plasma or by proton implantation. In both cases, when proper account is taken of shallow dopant passivation or compensation effects, there is a significant improvement in the reverse breakdown voltage of simple TiPtAu Schottky diodes. Proton implantation into undoped (n=3×1016 cm−3) GaAs-on-Si leads to an increase in this breakdown voltage from 20 to 30 V, whereas plasma hydrogenation improves the value from 2.5 to 6.5 V in n-type (2×1017 cm−3) GaAs-on-Si. Annealing above 550 °C removes the beneficial effects of the hydrogenation, coincident with extensive redistribution of the hydrogen. This leaves an annealing temperature window of about 50 °C in the H-implanted material, in comparison to 150 °C for the plasma-hydrogenated material. The hydrogen migrates out of the GaAs to both the surface and heterointerface, where it shows no further motion even at 700 °C. Trapping in the GaAs close to the heterointerface is shown to occur at stacking faults and microtwins, in addition to extended dislocations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.342547
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  • 8
    Digitale Medien
    Digitale Medien
    Infrared study of hydrogen- and carbon-implanted heavily doped, n-type GaAs (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 1936-1945 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A study is given of the effect of ion implantation on the carrier density and the infrared dielectric constant of heavily doped, high-carrier density, n-type GaAs as measured by infrared reflection. Hydrogen ions were implanted at 300 keV at room temperature and carbon ions at 380 keV at near-liquid-nitrogen temperature. For H and C ions the effects of the implantation and subsequent annealing from 100 to 550 °C are examined. The 1H ion implantation and annealing results are compared with available SIMS data and with the carrier density profile obtained from capacitance-voltage measurements of a progressively etched sample. The 1H and carrier compensation profiles are clearly related and show a compensated layer ∼3 μm thick for the as-implanted samples. A deeply diffused layer is present after annealing and the depth grows with anneal temperature. After 500 °C annealing the carrier compensation in the diffused layer disappears but the original layer is still compensated. The 12C-implanted sample shows both carrier compensation and substantial damage-related changes in the dielectric constant. Annealing removes the damage-related changes and no compensated diffused layer such as that observed for hydrogen was present. An effective diffusion constant for the hydrogen related defect can be estimated but its value is dependent upon the model used. Different models give Deff=D0effe−Ea/kT with Ea about 1 eV but with D0eff values which are strongly model dependent.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.336422
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  • 9
    Digitale Medien
    Digitale Medien
    Hydrogen depth profiles and optical characterization of annealed, proton-implanted n-type GaAs (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 3731-3734 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Depth profiles of 300-keV protons implanted in n-type GaAs at room temperature have been obtained using secondary ion mass spectrometry and correlated with optical effects determined by infrared reflectance measurements. The profiles of the implanted hydrogen (1H) have been measured as a function of annealing for temperatures up to 600 °C. These profiles display a major redistribution of the hydrogen atoms with movement beginning at 200 °C and terminating by 700 °C. The hydrogen diffusion into the substrate can be approximated by an Arrhenius process with an activation energy of 0.62 eV and a diffusion constant of 1.54×10−5 cm2/s. The reflectance spectra indicate that while an optically uniform layer is present in the as-implanted specimen, more complicated optical profiles exist in the annealed samples. Annealing at 300 °C causes the layer to nearly double in thickness but higher temperature annealing produces optical profiles similar to the as-implanted state. Qualitatively, these optical changes follow the behavior of the hydrogen depth profiles.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.335637
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  • 10
    Digitale Medien
    Digitale Medien
    Hydrogenation of GaN, AlN, and InN (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 2724-2726 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Hydrogen incorporation depths of ≥1 μm are measured for 2H plasma exposure of GaN and AlN at 250–400 °C for 30 min. The concentration of 2H incorporated is in the range 5–10×1017 cm−3 for GaN and 5–30×1018 cm−3 for AlN under these conditions. No redistribution of the hydrogen is observed for annealing temperatures up to 800 °C, but at 900 °C there is substantial loss of hydrogen from the samples. Similar results are obtained for 2H implantation into GaN, AlN, and InN, with no significant redistribution observed up to 500–600 °C in either AlN or InN, and motion only at 900 °C in GaN. The thermal stability of hydrogen in III-V nitrides explains previous results for Mg-doped GaN grown using NH3, where post-growth annealing at high temperatures was required to achieve appreciable doping efficiencies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.111455
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