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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 347-353 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: 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.
    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 66 (1989), S. 6055-6058 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Simultaneous depth profiles for H and Li have been measured in proton-exchanged lithium niobate crystals (LiNbO3) by the use of charge-compensated secondary ion mass spectrometry (SIMS). Electron flooding of the insulator during sputtering permits accurate depth profiling through the exchanged region and into the substrate. Four samples of z-cut proton-exchanged LiNbO3 were analyzed using SIMS, and were used in optical waveguiding experiments. In each sample, the H distribution is in the shape of a plateau that extends from the surface to a depth that is in good agreement with the results of the optical waveguiding measurements.The Li profiles show reduced concentrations within the regions of high H concentration, that is, within the waveguiding regions. Based on SIMS data, the proton-exchange process appears to stabilize at a value of 0.4〈x〈0.5 for the Li1−xHxNbO3 compound.
    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 65 (1989), S. 1968-1971 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: 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.
    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 63 (1988), S. 5302-5311 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured, using secondary-ion mass spectrometry, the (111) random and 〈110〉 channeled profiles for about 45 ions implanted into Hg1−xCdxTe. Ion energies vary from 100 to 700 keV, and ion fluences from 1×1013 to 3×1015 cm−2. The specially preannealed device-quality Hg1−xCdxTe substrates were implanted at room temperature and not annealed after implantation. Ions implanted include 1H(C), 2H(C), He, Li(C), Be(C), B(C), C(C), N(C), O(C), F(C), Na(C), Mg(C), Al(C), Si(C), P(C), S(C), Cl(C), K(C), Ca(C), Ti(C), V, Cr(C), Mn(C), Fe(C), Co(C), Ni, Cu(C), Zn, Ga, Ge, As, Se, Br(C), Kr, Rb, Zr, Mo(C), Ag, In(C), Sn, Sb, Cs, and Ta, where (C) means that 〈110〉 channeled profiles were measured in addition to (111) random orientation profiles. Other ions were implanted but with poor profiling results. We report here implantation range data that include the peak depth Rm, the projected range Rp or first moment μ, the range straggle ΔRp or second moment σ, the third moment or skewness γ1, and the fourth moment or kurtosis β2, obtained from a Pearson IV fitting routine, and the maximum 〈110〉 channeling range. We show what densities and depths can be achieved using 〈110〉 channeled implantation in solid-state recrystallized Hg1−xCdxTe. Values of electronic stopping Se are calculated from the maximum 〈110〉channeling ranges and show the Z1-dependent nature of Se.
    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 61 (1987), S. 933-939 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the results of a study of atom and acceptor depth profiles of unannealed and annealed Al implants into Si. We describe three regimes of Al redistribution during annealing, the characteristics of which depend on the density of the Al and associated defects. We also report as-implanted and annealed Al depth distributions, range parameters, and profile-shape factors for Al implanted into crystalline Si for energies from 20 to 600 keV and fluences from 3×1012 to 3×1016 cm−2.
    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 58 (1985), S. 3731-3734 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: 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.
    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 57 (1985), S. 2299-2301 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Depth distributions of 300-keV protons implanted in n-type GaAs and characteristics of the associated damage in the crystalline material have been obtained. Range profiles of the implanted 1H ions as a function of substrate implantation temperature have been determined using secondary ion mass spectrometry for fluences of 5×1014 and 5×1015 cm−2. The projected range for the protons was approximately 2.7 μm for the room temperature implants, but a significant rearrangement of the 1H atoms occurred during elevated temperature implantation. While cross-sectional transmission electron microscopy showed no evidence of crystal damage in as-implanted wafers, plan-view measurements revealed platelike damage structures in the surface region (〈 1μm).
    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. 5121-5125 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We implanted ions of 45 elements into HgCdTe, and into CdTe in some cases, at a variety of energies and fluences, and successfully measured the resulting depth distributions for 43 of them using oxygen and cesium primary ion beams and positive and negative secondary ion mass spectrometry (SIMS), respectively. Relative sensitivity factors for SIMS were determined for these elements in HgCdTe and CdTe using the known implantation fluences. The SIMS relative sensitivity factor is proportional to the inverse of the relative ion yield. We have plotted the results from oxygen SIMS and positive ions versus ionization potential (I), and from cesium SIMS and negative ions versus electron affinity (A) of the implanted elements. These data can be used to test models and theories about the dependence of positive and negative ion yield on I and A. Many of the data from oxygen SIMS for elements with ionization potential between 5 and 10 eV are consistent with the model of positive ion yield dependence on exp(−I), but some elements differ reproducibly and consistently from that model. Elements with ionization potential less than 5 eV and greater than 10 eV follow different dependencies. The data from Cs SIMS tend to fit the model of negative ion yield proportional to exp(+A), but no consistent single curve can be drawn through the data. The data for CdTe agree with those for HgCdTe within experimental error.
    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. 2489-2491 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report depth distributions of 200-keV He ions channeled in the 〈100〉 and 〈110〉 directions of Si, Ge, and GaAs crystals and in a random orientation of each crystal, measured using secondary ion mass spectrometry. The 〈100〉 channeled profiles agree with the random profiles within experimental error. The 〈110〉 channeled profiles are about 1.7, 2.3, and 2.2 times as deep as the random peaks (projected range) for the three crystals, respectively. Assuming velocity-proportional electronic stopping, values of electronic stopping are calculated for He in Si, Ge, and GaAs. Fractions of He ions backscattered into the vacuum are estimated. Profiles for Ge and GaAs, with the same average atomic number, are compared. Range and profile shape parameters are tabulated.
    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 60 (1986), S. 2797-2805 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured implanted and annealed depth distributions for the two elements adjacent to Si, Al, an acceptor in Si, and P, a donor in Si, using secondary ion mass spectrometry for the atom depth distributions and differential capacitance-voltage profiling for the acceptor or donor depth distributions. Ions of Al or P were implanted into Si amorphized by Si implantation, into crystalline Si in a random orientation, and channeled into the three principal low index directions of the Si lattice, 〈100〉, 〈110〉, and 〈111〉. The ion energies were 25, 50, 75, 100, 150, 200, 300, 400, or 600 keV and the ion influences were 3×1013, 3×1014, and 3×1015 cm−2 for the atom depth distributions, and 1.5×1012 cm−2 for the acceptor and donor profiles. Pearson IV fitting was used to obtain the values of the first four moments of the random depth distributions, the projected range Rp or μ, the range straggle ΔRp or standard deviation σ, the skewness γ1, and the kurtosis β2. For the channeling orientations, the maximum channeling range or the depth of the channeled peak are plotted versus ion energy, and values of the energy exponent p are determined. The random ranges Rp and profiles are compared for amorphized and crystalline Si and compared with range calculations; the profiles in amorphized Si are modified Gaussians as predicted by theory, with no channeling tails, and the profiles in crystalline Si have significant channeling tails that are not easily fit to a modified Gaussian. The different channeling profiles for Al and P are illustrated and explained in terms of their different electronic stopping and ion size. The effects of 30-min furnace annealing at 550 and 800 °C are shown for implanted Al profiles; significant redistribution occurred, and in a manner that depends on Al atom density and whether the Si is amorphous or crystalline. Furnace annealing at 875 and 925 °C or rapid radiant annealing at 900 °C caused no redistribution of P profiles implanted at room temperature.
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