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  • 1
    Electronic Resource
    Electronic Resource
    Zero-field time-of-flight characterization of minority-carrier transport in heavily carbon-doped GaAs (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 7471-7477 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Minority-carrier electron-diffusion coefficients and lifetimes have been measured in heavily doped p-type GaAs using the zero-field time-of-flight (ZFTOF) technique. The materials studied included C-doped GaAs grown by molecular-beam epitaxy (MBE) using graphite as the dopant source, C-doped GaAs grown by metalorganic chemical-vapor deposition (MOCVD) using CCl4 as the dopant source, and Be-doped GaAs grown by MBE. Room-temperature photoluminescence intensity measurements were made on the structures and the results are compared with ZFTOF measurements of lifetime. The graphite-doped material (p∼1019 cm−3) exhibited diffusion lengths of less than 1000 A(ring). MOCVD-grown C-doped GaAs, which was optimized by adjusting the growth conditions to maximize the room-temperature photoluminescence intensity, had diffusion lengths comparable to those measured in Be-doped GaAs for hole concentrations of 1×1019 and 5×1019 cm−3. Comparison of photoluminescence intensities also suggests that addition of In to very heavily doped MOCVD-grown GaAs (p(approximately-greater-than)1020 cm−3) to eliminate the lattice mismatch with respect to the substrate does not result in an improvement in lifetime.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353991
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  • 2
    Electronic Resource
    Electronic Resource
    Characterization of heavily carbon-doped GaAs grown by metalorganic chemical vapor deposition and metalorganic molecular beam epitaxy (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 981-987 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Carbon-doped GaAs with carbon concentrations ranging from 2×1017 cm−3 to 2.6×1020 cm−3 has been characterized by variable temperature Hall effect measurements, secondary ion mass spectrometry (SIMS), and double-crystal x-ray diffraction (DCXD). The samples studied were grown by metalorganic chemical vapor deposition (MOCVD) and by metalorganic molecular beam epitaxy (MOMBE). The hole mobility is dominated by degenerate conduction for hole concentrations ≥1×1019 cm−3, and the 77 K resistivity is typically 30%–35% lower than at 300 K in these samples. The mobilities of C-doped p+-GaAs are found to be significantly higher than for Zn- or Be-doped p+-GaAs for doping concentrations in excess of 2×1018 cm−3. The maximum achievable hole mobilities for C-doped material grown by the two techniques are nearly identical, indicating that neither MOCVD nor MOMBE has an inherent advantage over the other for producing low-resistivity p-type GaAs. SIMS analysis and Hall effect measurements reveal that the total carbon concentration, [C], is higher than the as-grown hole concentration, p, in the most heavily doped samples. DCXD measurements show general agreement with the lattice mismatch predicted by Vegard's law. However, for [C](approximately-greater-than)1020 cm−3 a discrepancy between the predicted and measured mismatch suggests that partial lattice relaxation or the presence of interstitial carbon may need to be considered in order to adequately describe the lattice contraction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351776
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  • 3
    Electronic Resource
    Electronic Resource
    Carbon incorporation in InP grown by metalorganic chemical vapor deposition and application to InP/InGaAs heterojunction bipolar transistors (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 4233-4236 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The incorporation of residual carbon has been studied for InP grown at low temperatures using TMIn and PH3 by low-pressure metalorganic chemical vapor deposition. n-type conduction is observed with electron concentrations as high as 1×1018 cm−3, and the electrical activation efficiency is 5%–15%. Carbon incorporation is found to be highly dependent on substrate temperature, suggesting that the rate-limiting step is desorption of CHy (0≤y≤3) from the surface during growth. Hydrogen is also incorporated in the layers during growth. The electron mobilities are lower for C-doped InP than for Si-doped InP. InP/InGaAs heterojunction bipolar transistors with C as the p-type base dopant and either Si or C as the n-type emitter dopant have been fabricated and compared. Devices with a carbon-doped base and emitter showed degraded performance, likely as a result of deep levels incorporated during growth of the emitter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356011
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  • 4
    Electronic Resource
    Electronic Resource
    Growth-induced shallow acceptor defect and related luminescence effects in molecular beam epitaxial GaAs (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 741-754 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a study of a defect responsible for the "g'' bound exciton line at 1.5112 eV that is frequently detected in photoluminescence spectra of GaAs grown by molecular beam epitaxy (MBE). A direct correlation has been observed between this line and a transition at 1.4946 eV, which is shown to result from a conduction band-to-acceptor recombination involving a shallow, unidentified acceptorlike defect that is labeled "A.'' The activation energy of the defect is 24.8±0.2 meV, about 1.7 meV lower than that of CAs acceptor. Upon hydrogenation the defect is passivated more extensively than any known shallow acceptor species in GaAs. This result is analyzed in terms of a passivation model, from which it can be inferred that the A defect is not due to a simple substitutional Group II impurity on a Ga site. Incorporation of the A defect strongly affects the luminescence properties of the material. An almost complete quenching of the donor-bound exciton lines, profound changes in the line shape and relative intensity of the free exciton recombination, and appearance of a sharp transition of unknown origin at 1.5138 eV were observed with increasing defect concentration. Apparently "donorless'' low temperature exciton recombination spectra are reported for defect-rich p-type MBE GaAs layers with donor concentrations as high as 7×1014 cm−3 and compensation ratios of ∼0.3. The dependence of the defect incorporation on MBE growth parameters is discussed. The feasibility of MBE growth of high purity, nearly shallow defect-free p-type GaAs layers at marginally As-stabilized surface conditions over an about 1–5 μm/h range of deposition rates is demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346779
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  • 5
    Electronic Resource
    Electronic Resource
    Acceptor diffusion and segregation in (AlxGa1−x)0.5In0.5P heterostructures (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 4891-4899 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Acceptor segregation is investigated as a function of compositional difference, Δx, between adjacent layers in (AlxGa1−x)0.5In0.5P heterostructures. Magnesium, Zn, Be, and Mn acceptor species are all shown to segregate out of the high band gap Al-rich (AlxGa1−x)0.5In0.5P layers and into the low band gap Al-poor (AlxGa1−x)0.5In0.5P layers during high temperature epitaxial growth of such heterostructures. The observed acceptor segregation appears to be independent of growth method or dopant incorporation method (metalorganic chemical vapor deposition, gas source molecular-beam epitaxy, or ion implantation), and increases with increasing compositional difference between adjacent (AlxGa1−x)0.5In0.5P layers. A theoretical model is developed to describe acceptor segregation based on charge separation and the resulting electric field across the heterointerface, and the resulting acceptor segregation is shown to vary as (mh AL*/mh CL*)3/2 exp(ΔEV/kT) where mh AL* and mh CL* are the hole effective masses in the active layer and confining layer, and ΔEV is the valence band offset. Comparison between experimentally measured and theoretically predicted acceptor segregation ratios gives excellent agreement for (AlxGa1−x)0.5In0.5P heterostructures over the range of compositional differences from Δx=0.12 to Δx=0.93. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1461060
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  • 6
    Electronic Resource
    Electronic Resource
    High-power AlGaInN flip-chip light-emitting diodes (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 3379-3381 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Data are presented on high-power AlGaInN flip-chip light-emitting diodes (FCLEDs). The FCLED is "flipped-over" or inverted compared to conventional AlGaInN light-emitting diodes (LEDs), and light is extracted through the transparent sapphire substrate. This avoids light absorption from the semitransparent metal contact in conventional epitaxial-up designs. The power FCLED has a large emitting area (∼0.70 mm2) and an optimized contacting scheme allowing high current (200–1000 mA, J∼30–143 A/cm2) operation with low forward voltages (∼2.8 V at 200 mA), and therefore higher power conversion ("wall-plug") efficiencies. The improved extraction efficiency of the FCLED provides 1.6 times more light compared to top-emitting power LEDs and ten times more light than conventional small-area (∼0.07 mm2) LEDs. FCLEDs in the blue wavelength regime (∼435 nm peak) exhibit ∼21% external quantum efficiency and ∼20% wall-plug efficiency at 200 mA and with record light output powers of 400 mW at 1.0 A. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1374499
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  • 7
    Electronic Resource
    Electronic Resource
    1.4× efficiency improvement in transparent-substrate (AlxGa1−x)0.5In0.5P light-emitting diodes with thin (≤2000 Å) active regions (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 2230-2232 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Improvement of 1.4× in the external quantum efficiency and luminous efficiency (lm/W) of transparent-substrate (AlxGa1−x)0.5In0.5P/GaP light-emitting diodes is demonstrated. The improvement is accomplished by reducing the thickness of the active layer to ≤2000 Å and increasing the internal quantum efficiency by using multiple thin (≤500 Å) active layers. The maximum luminous efficiency achieved is 73.7 lm/W at λp∼615 nm and the maximum external quantum efficiency is 32.0% at λp∼632 nm. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123810
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  • 8
    Electronic Resource
    Electronic Resource
    High-power truncated-inverted-pyramid (AlxGa1−x)0.5In0.5P/GaP light-emitting diodes exhibiting 〉50% external quantum efficiency (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 2365-2367 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A truncated-inverted-pyramid (TIP) chip geometry provides substantial improvement in light extraction efficiency over conventional AlGaInP/GaP chips of the same active junction area (∼0.25 mm2). The TIP geometry decreases the mean photon path-length within the crystal, and thus reduces the effects of internal loss mechanisms. By combining this improved device geometry with high-efficiency multiwell active layers, record-level performance for visible-spectrum light-emitting diodes is achieved. Peak efficiencies exceeding 100 lm/W are demonstrated (100 mA dc, 300 K) for orange-emitting (λp∼610 nm) devices, with a peak luminous flux of 60 lumens (350 mA dc, 300 K). In the red wavelength regime (λp∼650 nm), peak external quantum efficiencies of 55% and 60.9% are measured under direct current and pulsed operation, respectively (100 mA, 300 K). © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125016
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  • 9
    Electronic Resource
    Electronic Resource
    Growth of carbon-doped p-type InxGa1−xAs (0〈x≤0.53) by metalorganic chemical vapor deposition (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 2903-2905 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Carbon doping of InxGa1−xAs grown on GaAs and InP substrates by low-pressure metalorganic chemical vapor deposition (LP-MOCVD) using CCl4 has been investigated for In mole fractions as high as x=0.53. P-type conduction was obtained over the entire composition range studied, with hole concentrations above 1×1020 cm−3 for x〈0.12, and as high as 1×1019 cm−3 for In0.53Ga0.47As lattice-matched to InP. These high carbon concentrations were achieved by employing very low V/III ratios and low growth temperatures. The alloy composition was found to be dependent on several growth parameters, including CCl4 partial pressure, V/III ratio, and growth temperature. This may be due to surface reactions (etching) involving chlorine-containing compounds during growth. Samples grown at low temperature (∼500 °C) and lattice matched to InP exhibited an increase in hole concentration upon post-growth annealing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106814
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  • 10
    Electronic Resource
    Electronic Resource
    Minority carrier transport in carbon doped gallium arsenide (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 65-67 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Minority carrier electron mobilities and diffusion lengths in p-type C-doped GaAs have been measured at room temperature and 77 K using the zero field time of flight (ZFTOF) technique on p+–n structures with p+ carrier concentrations of 1.1×1019, 6.0×1018, 1.8×1018 cm−3, which were grown by low-pressure metalorganic chemical vapor deposition (MOCVD) using CCl4 as the dopant. The electron mobilities obtained are higher than those reported for Be-doped MBE GaAs but lower than those reported for Ge-doped, LPE GaAs, while the diffusion lengths are similar to those found in similar concentration Be-doped samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107375
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