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  • 1
    Electronic Resource
    Electronic Resource
    Temperature dependence of reactive ion etching of GaAs with CCl2F2:O2 (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 3839-3849 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The etch rate of GaAs during reactive ion etching (RIE) in a CCl2F2:O2 discharge (4 mTorr, 0.56 W cm−2) shows a strong temperature dependence, increasing from ∼500 A(ring) min−1 at 50 °C to 2800 A(ring) min−1 at 400 °C. Arrhenius plots of the etch rate show two activation energies (0.17 eV from 50 to 150 °C and 0.11 eV from 150 to 400 °C). There is no significant plasma power density dependence of the etch rate at elevated temperatures (≥100 °C) in contrast to the strong dependence at 50 °C. The surface morphology undergoes smooth-to-rough-to-smooth-to-rough transitions at ∼150, 250, and 400 °C, respectively, although TiPtAu Schottky diodes exhibit near-ideal behavior on GaAs etched at 150 °C. The As-to-Ga ratio in the first 100 A(ring) from the surface increases with increasing RIE temperature, with chloride residues absent above 150 °C. Fluorocarbon residues were present on all samples, but were limited to the first 10–15 A(ring). As determined by x-ray photoelectron spectroscopy, fluorine was present almost exclusively as metallic gallium fluorides, while oxygen was present as both Ga and As oxides. Ion channeling detected lattice disorder to depths of ∼200 A(ring) for etch temperatures from 50 to 250 °C, while there was less damage for etching at 400 °C. No new RIE-induced deep levels were observed by capacitance transient spectroscopy in any of our samples, although the concentration of the midgap donor EL2 increased with increasing temperature during the RIE process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344048
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  • 2
    Electronic Resource
    Electronic Resource
    Characterization of InP/GaAs/Si structures grown by atmospheric pressure metalorganic chemical vapor deposition (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 1083-1088 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The thickness dependence of material quality of InP-GaAs-Si structures grown by atmospheric pressure metalorganic chemical vapor deposition was investigated. The InP thickness was varied from 1–4 μm, and that of the GaAs from 0.1–4 μm. For a given thickness of InP, its ion channeling yield and x-ray peak width were essentially independent of the GaAs layer thickness. The InP x-ray peak widths were typically 400–440 arcsec for 4-μm-thick layers grown on GaAs. The GaAs x-ray widths in turn varied from 320–1000 arcsec for layer thicknesses from 0.1–4 μm. Cross-sectional transmission electron microscopy showed high defect densities at both the InP-GaAs and GaAs-Si interfaces. In 4-μm-thick InP layers the average threading dislocation density was in the range (3–8)×108 cm−2 with a stacking fault density within the range (0.4–2)×108 cm2. The He+ ion channeling yield near the InP surface was similar to that of bulk InP (χmin∼4%), but rose rapidly toward the InP-GaAs heterointerface where it was typically around 50% for 1-μm-thick InP layers. All samples showed room-temperature luminescence, while at 4.4 K, exciton-related transitions, whose intensity was a function of the InP thickness, were observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343043
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  • 3
    Electronic Resource
    Electronic Resource
    Implantation temperature dependence of electrical activation, solubility, and diffusion of implanted Te, Cd, and Sn in GaAs (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 1089-1098 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The relationship between electrical activity, dopant solubility, and diffusivity was investigated as a function of the substrate temperature during implantation of Te, Cd, and Sn ions into GaAs. Implant doses of these species in the range 5×1012–5×1015 cm−2 were performed in the temperature range −196 to 400 °C, followed by either transient (950 °C, 5 s) or furnace (450–900 °C, 20 min) annealing. The redistribution after such annealing was found to depend on the implant temperature, and was always greatest for Cd followed by Sn and Te. The degree of electrical activation was in the same order, but there was essentially no correlation of electrical activity with dopant solubility. Te, for example, showed soluble fractions of ∼90% for a dose of 1015 cm−2 after annealing at 850 °C or higher, regardless of the initial implant temperature. By sharp contrast, the electrically active fraction under these conditions was in the range 0.8%–3.4%. There was also no apparent correlation of the degree of electrical activity with the presence of defects visible in transmission electron microscopy. The energy required to activate the implanted ions fell broadly into two categories: "low'' values in the range ∼0.4–0.8 eV (which included Cd implanted or annealed under any condition, and elevated temperature implants of Sn and Te), and "high'' values in the range 1.7–1.9 eV [which included implants of Sn and Te performed at −196 °C, or high dose (1015 cm−2) room-temperature implants of these species].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343044
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  • 4
    Electronic Resource
    Electronic Resource
    The role of crystal-growth properties on silicon implant activation processes for GaAs (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 1464-1467 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Crystal properties such as bulk resistivity, mobility, and dislocation density which influence ion-implantation activation are reported for liquid-encapsulated Czochralski, horizontal gradient freeze, and vertical gradient freeze semi-insulating GaAs crystals. The liquid-encapsulated Czochralski crystals used in this study include as-grown, boule-annealed, and indium-alloyed GaAs. Wafer maps displaying the concentration and spatial distribution of neutral EL2 are presented for each crystal. Wafers from the various crystals were implanted with 29Si at a dose of 3×1012 ions/cm2 and an energy of 60 keV. Macroscopic variations in the donor distribution and peak carrier density demonstrate that point defects impact significantly the donor implant activation processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341818
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  • 5
    Electronic Resource
    Electronic Resource
    Ion implantation damage and annealing in InAs, GaSb, and GaP (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 629-636 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The characteristics of ion implantation induced damage in InAs, GaSb, and GaP, and its removal by rapid thermal annealing have been investigated by Rutherford backscattering and transmission electron microscopy. There is relatively poor regrowth of these materials if they were amorphized during the implantation, leaving significant densities of dislocation loops, microtwins, and in the case of GaSb, polycrystalline material. For implant doses below the amorphization threshold, rapid annealing produces good recovery of the lattice disorder, with backscattering yields similar to unimplanted material. The redistribution of the implanted acceptor Mg is quite marked in all three semiconductors, whereas the donor Si shows no measurable motion after annealing of InAs or GaP. In GaSb, however, where it appears to predominantly occupy the group III site, it shows redistribution similar to that of Mg.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341952
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  • 6
    Electronic Resource
    Electronic Resource
    Implantation characteristics of InSb (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 1942-1946 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Damage introduction by implantation of Be and Si into InSb, and its removal by rapid thermal annealing in the range 300–400 °C for 20 s was investigated by Rutherford backscattering and transmission electron microscopy. There is good recovery of the lattice upon annealing at 450 °C provided the InSb was not amorphized during the implantation step. At the same time, there is limited redistribution of Be for these annealing conditions, but for Si there is marked diffusion even during a nominal room-temperature implant. Lowering the sample temperature to 77 K during the implant stops this redistribution, with a near-Gaussian ion distribution resulting. The activation of Be is of the order of 50% over the dose range 1013–1015 cm−2. In most cases there is a marked similarity in implant properties of InSb to those of GaSb.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344329
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  • 7
    Electronic Resource
    Electronic Resource
    Reactive ion etching of GaAs with CCl2F2:O2: Etch rates, surface chemistry, and residual damage (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 1281-1292 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The reactive ion etching of GaAs with a CCl2F2:O2 discharge was investigated as a function of gas flow rate (10–60 sccm), total pressure (2–50 mTorr), power density (0.25–1.31 W cm−2), gas composition (0%–70% O2), and etch time (1–64 min). The etch rate decreases with increasing gas flow rate, increases with increasing power density, and goes through a maximum at a gas composition of 75:25 CCl2F2:O2 under our conditions. After etching at low-power densities (0.56 W cm−2) and for high CCl2F2 ratios (19:1 to O2), carbon and chlorine could be detected in the GaAs to a depth of less than 15 A(ring) by x-ray photoelectron spectroscopy. Under these conditions there was a Ga deficiency to a depth of ∼100 A(ring), which we ascribe to surface roughening and the preferential vaporization of As2O3 over Ga2O3. At high-power densities (1.31 W cm−2) a polymeric layer several hundred angstroms thick containing CCl and CF bonds was observed on the GaAs surface. Etching under O2-rich conditions did not lead to any additional creation of surface oxides. Both ion channeling and electron microscopy detected a thin disordered layer on the GaAs after etching. Small (〈100 A(ring) diam) dislocation loops were present at a depth varying from ∼400 A(ring) for 0.56 W cm−2 (380-V self-bias) plasma power density to ∼2200 A(ring) for 1.31 W cm−2 (680-V self-bias). The disorder was stable against a 500 °C annealing treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343023
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  • 8
    Electronic Resource
    Electronic Resource
    Thickness dependence of material quality in GaAs-on-Si grown by metalorganic chemical vapor deposition (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 775-783 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The evolution with increasing layer thickness of the structural and electrical properties of GaAs grown directly on Si or Si-on-insulator (SOI) by metalorganic chemical vapor deposition is reported. There is a substantial improvement in the surface morphology and near-surface crystallinity of the GaAs in thicker films (≥1.5 μm). The implant activation efficiency of 60-keV 29Si ions at a thickness of 4 μm is comparable to that seen in bulk GaAs. The deep level concentration is also observed to decrease with increasing layer thickness. Transmission electron microscopy reveals average defect densities near 108 cm−2 in films deposited either on misoriented or exact (100) Si, and in those grown on SOI.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341141
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  • 9
    Electronic Resource
    Electronic Resource
    Characterization of GaAs layers grown directly on Si substrates by metalorganic chemical vapor deposition (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 862-867 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electrical and structural properties of GaAs layers grown directly by metalorganic chemical vapor deposition on Si substrates oriented 2° off (100) toward [011] are reported. The uniformity of minority-carrier lifetime in the 2 in.- diam heteroepitaxial wafers is comparable to that in bulk GaAs of the same doping density (2×1016 cm−3). Selective etching of the GaAs layer reveals an etch pit density of ∼108 cm−2, consistent with plan view transmission electron microscopy which shows a defect density of ∼108 cm−2. Rapid annealing at 900 °C for 10 s does not significantly alter the heterointerface abruptness, and at the same time the crystalline quality of the GaAs improves slightly. The deep level concentration in the as-grown layer is ∼1013 cm−3 as determined by capacitance spectroscopy. Finally, the activation characteristics of low dose Si implants (3×1012 cm−2 at 60 keV) are similar to those in high quality bulk GaAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339690
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  • 10
    Electronic Resource
    Electronic Resource
    Characterization of n-type regions in GaAs formed by silicon fluoride molecular ion implantations (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 4176-4180 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Implantations of silicon and silicon fluoride ions into semi-insulating GaAs wafers were performed to compare and evaluate the quality of the n-type layers that were produced. The use of SiFx (x=1,2,3) molecular ion implantations creates n-type active regions and n+ ohmic contact layers employing a higher implant energy than that needed to achieve a similar projected range for silicon ions. The higher energy allows the implanter to operate with a more stable and reproducible ion beam for shallow implant applications. Variables affecting the net electrically active ion distributions, such as the ion beam incidence angle, and the use of furnace or rapid thermal annealing cycles for implantation activation are addressed. Capacitance-voltage profiles were obtained for the n-type regions, and the free carrier distributions for the n+ implantations were obtained by polaron electrolytic profiling. The implanted regions were characterized by Hall-effect measurements, cathodoluminescence, and secondary ion mass spectroscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344002
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