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  • 1
    Electronic Resource
    Electronic Resource
    Interdiffusion in alloys of the GaInAsP system (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 4903-4915 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Interdiffusion experiments and results for InP-GaInAs(P) heterostructures are reviewed and discussed within a thermodynamic model. Important factors affecting interdiffusion in the GaInAsP system are shown to include the (1) miscibility gap, (2) different diffusivities on each sublattice in each material, (3) Fermi level or impurity induced changes in diffusivity and perhaps diffusion mechanism, and (4) experimental technique chosen. With a miscibility gap present, the activity coefficients and solubilities of all species vary near a heterojunction and cause the interdiffusion to become strongly composition dependent. At commonly used growth and annealing temperatures, many superlattices are expected to equilibrate as two quaternary superlattices rather than a homogeneous alloy. Different diffusivities on each sublattice in a superlattice can lead to either a widening or a narrowing of quantum wells. When this occurs, optical measurements of the band gap energy are likely to be misleading because of quantum size effects. Diffusivity on each sublattice can be changed by the presence of group II, IV, or VI dopants. Diffusion on the group III sublattice in p-type GaInAsP is found to be consistent with an interstitialcy mechanism, but the mechanism remains unknown with n-type doping and for the group V sublattice. Diffusion experiments performed in closed, open, and capped environments are discussed. Poorly designed and controlled experiments are found to be associated with large discrepancies in observed diffusivities, unreliable concentration profiles, and new condensed phases appearing in the solid. Experiments to date indicate that the Cu-Pt ordered structure often found in GaIn(As)P epilayers are unstable, and not strain stabilized, relative to the disordered structure at commonly used growth and annealing temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353808
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  • 2
    Electronic Resource
    Electronic Resource
    Investigation of organometallic vapor phase epitaxy of InAs and InAsBi at temperatures as low as 275 °C (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 3940-3942 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: InAs and InAsBi have been grown by atmospheric pressure organometallic vapor phase epitaxy (OMVPE) over a broad temperature range from 600 to as low as 275 °C. This is the lowest growth temperature ever reported for standard OMVPE. It is demonstrated that lowering the growth temperature is the most effective approach for increasing the Bi content in InAsBi alloys. For example, InAsBi samples with Bi concentrations as high as 6.1 at.% have been successfully grown at a temperature of 275 °C. Trimethylindium, arsine, and trimethylbismuth were used as precursors for most experiments. The growth efficiency is a constant for temperatures above 400 °C, indicating the growth rate is diffusion limited in this temperature regime. For lower temperatures, it decreases exponentially with decreasing temperature with an activation energy of 24 kcal/mol. Incomplete pyrolysis of TMIn limits the growth rate in this temperature regime. However, by substituting ethyldimethylindium for TMIn the diffusion controlled regime can be extended to lower temperatures. Hall effect measurements show that the n-type background concentration increases from approximately 2.3×1016 to 1019 cm−3 as the growth temperature decreases from 600 to 325 °C. Secondary-ion mass spectroscopy results show that the dominant impurity is carbon. Thus, carbon is mainly a donor in these materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349204
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  • 3
    Electronic Resource
    Electronic Resource
    Organometallic vapor-phase epitaxy growth and characterization of Bi-containing III/V alloys (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 4586-4591 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: For potential infrared detector applications, single-crystalline InAsBi and InAsSbBi have been grown by atmospheric pressure organometallic vapor-phase epitaxy. The precursors used were trimethylindium, trimethylantimony, trimethylbismuth, and arsine at growth temperatures of 375 and 400 °C. Good quality epilayers with smooth surface morphologies were obtained by properly controlling the key growth parameter, the V/III ratio. The variation of lattice constant with solid composition for the InAs1−xBix system, a=6.058+0.966x, provides evidence that Bi atoms indeed incorporate substitutionally into the As sites of the sublattice in the InAs zinc-blende structure. An extrapolated lattice parameter for the hypothetical zinc-blende InBi is 7.024 A(ring). Thermodynamic calculations of the InAs-InBi and InSb-InBi pseudobinary phase diagrams were carried out using the delta-lattice-parameter model using the lattice constant for zinc-blende InBi of 7.024 A(ring). The results agree well with experimental data. The calculations predict that the solid solubility limit of Bi in InAs is less than 0.025 at. %. The calculated maximum solubility limit is 2.1 at. % for Bi in InSb at the eutectic temperature of 132 °C. Thus, tremendously large miscibility gaps exist in both alloy systems. The critical temperature was predicted to be 2569 °C for the InAs-InBi system and 496 °C for the InSb-InBi system. The miscibility gap is the major factor limiting Bi incorporation into the InAsSb alloys. Nevertheless, metastable InAsBi and InAsSbBi alloys were grown with concentrations far exceeding the solubility limit. For example 3.1 at. % Bi was incorporated into InAs. Infrared photoluminescence measurements show a decrease of peak energy with increasing Bi concentration in the alloys, with dEg/dx=−55 meV/at. %Bi.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346166
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  • 4
    Electronic Resource
    Electronic Resource
    Photoluminescence of InAsBi and InAsSbBi grown by organometallic vapor phase epitaxy (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 1187-1191 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Infrared photoluminescence (PL) from InAsBi and InAsSbBi epitaxial layers grown by atmospheric pressure organometallic vapor phase epitaxy has been studied. The PL from ternary InAsBi was investigated for Bi concentrations of ≤2.3 at. %. The peak energy decreases at a rate of 55 meV/at. % Bi with increasing Bi concentration. A study of the transmission spectra of these Bi-containing alloys confirms the above result. The PL peak is assigned to near band edge emission for InAsBi. The value of dEg/dx=−55-meV/at. % Bi is more than double the previously reported theoretical prediction for the band gap of InAsBi. The PL for the quaternary layer of InAsSbBi is also studied for Sb concentrations of 〈10 at. % and Bi concentrations of ≤1.5 at. %. Bi incorporation in InAs1−xSbx(0.07〈x〈0.10) reduces the PL peak energy at a rate of 46-meV/at. % Bi. These results imply that incorporation of only a few percent of Bi is required in InAs0.35Sb0.65 to achieve a band gap of 0.1 eV, equivalent to a wavelength of 12 μm, desired for infrared detector applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346715
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of mismatch strain on band gap in III-V semiconductors (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 5428-5432 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Interfacial elastic strain induced by the lattice parameter mismatch between epilayer and substrate results in significant energy–band-gap shifts for III-V alloys. The epilayers used in this study are GaxIn1−xAs on (100) InP and GaxIn1−xP on (100) GaAs prepared by organometallic vapor phase epitaxy. For layer thicknesses between 1 and 1.5 μm, and Δas.f./a0≤3.5×10−3 the misfit strain is assumed to be accommodated elastically. The energy–band-gap shifts are determined by comparing the photoluminescence peak energies of the epilayers with the best experimental relation of band gap versus composition for unstrained layers. A calculation of the energy–band-gap shift due to biaxial stress made for GaxIn1−xAs is found to agree with the photoluminescence measurements. In addition, a comparison of the energy–band-gap shift for GaxIn1−xP shows a clearly different dependency for tensile and compressive strain, in good agreement with calculated results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.334817
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  • 6
    Electronic Resource
    Electronic Resource
    Raman and photoluminescence spectra of GaAs1−xSbx (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 4817-4819 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The first experimental Raman and photoluminescence spectra are presented for the metastable alloy GaAs1−xSbx grown by organometallic vapor phase epitaxy throughout its miscibility gap extending from x=0.2 to x=0.75. The phonon peak halfwidths are found to broaden by nearly a factor of 2 over halfwidths found in the binary compounds GaAs and GaSb. Phonon line shapes become more asymmetric in the miscibility gap as the selection rules break down; in addition, a second peak appears for samples grown near the center of the miscibility gap. Line shapes are analyzed and the phonon coherence length is found to be reduced from several hundred angstroms in GaAs to approximately 60 A(ring) in samples grown in the miscibility gap. The compositional dependence of the room-temperature band-gap energy has been found to closely follow earlier predictions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335299
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  • 7
    Electronic Resource
    Electronic Resource
    Incorporation of Zn in GaAs during organometallic vapor phase epitaxy growth compared to equilibrium (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 1902-1906 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The zinc concentration measured after organometallic vapor phase epitaxy (OMVPE) growth on (100)-oriented GaAs at 700 °C has been compared to the zinc concentration measured after in-diffusion under near-equilibrium conditions. During diffusion, the concentration of Zn 20 nm below the surface was found to vary with P1/2Zn, as expected for bulk solid–vapor equilibrium. During growth, the concentration of Zn varied linearly with PZn up to a maximum value which was found to correspond to the solubility limit set by second phase formation, e.g., growth of Zn3As2. Although large differences were observed between the results of the two experiments when using nominally identical ambient conditions, all of the results are consistent with a thermodynamic model in which the Fermi level at the surface is pinned approximately 200 meV below the intrinsic Fermi level. Typical OMVPE growth conditions appear to give a bulk zinc concentration which is supersaturated relative to the ambient partial pressures used, and to enhance the diffusion of Zn into the substrate. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358821
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  • 8
    Electronic Resource
    Electronic Resource
    InAsSbBi alloys grown by organometallic vapor-phase epitaxy (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 2857-2863 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A major remaining challenge for III/V semiconductor materials is the development of materials for photonic devices operating in the infrared region of the spectrum. Atmospheric transmission windows exist in the wavelength ranges from 2 to 4.5 and from 8.5 to 12 μm. Thus, emitters and, particularly, detectors operating in these wavelength ranges are important for many applications. Materials for devices operating in the longer-wavelength 8–12 μm region have typically not been III/V semiconductors because the lowest-band-gap conventional III/V alloy is InAsSb, with a 77 K band gap of 0.145 eV, corresponding to a wavelength of 8.5 μm. Previous work has shown that the addition of Bi to InAsSb alloys grown by organometallic vapor-phase epitaxy results in a rapid reduction in the band-gap energy. However, very low temperatures were required to obtained significant levels of Bi incorporation into the solid, due to the immiscibility of Bi in InAsSb. The low growth temperatures result in high carbon contamination levels using conventional precursors. Clearly, new precursors are required for low-temperature growth of these alloys without excessive levels of carbon contamination. New results for the organometallic vapor-phase-epitaxy growth of InAs1−x−ySbxBiy alloys are presented using the novel precursors tertiarybutylarsine, tertiarybutyldimethyl-antimony, and ethyldimethylindium. Alloys have been studied over the entire range of Sb/As ratios in the solid. For growth at 350 °C, the maximum Bi concentration yielding layers without the presence of a liquid second phase was found to be highest for x=0 (y=0.045) and lowest for x=0.7 (y=0.015). These levels of Bi incorporation yield calculated 77 K band gaps of 0.08 eV for the alloy with x=0.5 and y=0.015. These layers have several orders of magnitude lower levels of carbon contamination than reported previously.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356179
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  • 9
    Electronic Resource
    Electronic Resource
    Organometallic vapor phase epitaxial growth and characterization of InAsBi and InAsSbBi (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2420-2422 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: InAs1−xBix with x≤0.026 and InAs1−x−ySbyBix with x≤0.017 and y≤0.096 have been successfully grown on InAs (100) oriented substrates by atmospheric pressure organometallic vapor phase epitaxy using the precursors trimethylindium, trimethylbismuth, trimethylantimony, and arsine. Good surface morphologies for both InAsBi and InAsSbBi epitaxial layers were obtained at a growth temperature of 400 °C. A key growth parameter is the V/III ratio. Only a very narrow range near 4 (considering the incomplete pyrolysis of AsH3) yields smooth InAsBi epilayers. Typical growth rates were 0.02 μm/min. X-ray diffractometer scans show clearly resolved Kα1 and Kα2 peaks for the layer of InAs0.889Sb0.096Bi0.015 grown on an InAs substrate with a graded transition layer to accommodate the lattice parameter difference. The half widths of the peaks are comparable to those of the substrate. For the first time, photoluminescence (PL) at 10 K from these Bi-containing alloys has been measured. The PL peak energy is seen to decrease with increasing Bi concentration at a rate of 55 meV/at. % Bi. InAsSbBi is a potential material for infrared detectors operating in the wavelength range from 8 to 12 μm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102033
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  • 10
    Electronic Resource
    Electronic Resource
    Organometallic growth and characterization of GaxIn1−xP (x=0.51, 0.65, 0.69) (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 1346-1351 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The growth and characterization of GaxIn1−xP (x=0.51, 0.65, 0.69) are described in this paper. The organometallic vapor-phase epitaxial (OMVPE) growth was carried out in an atomospheric pressure reactor using trimethylgallium (TMGa), trimethylindium (TMIn), and phosphine (PH3). GaAs and commercially available hydride vapor-phase epitaxial GaAs0.70P0.30 and GaAs0.61P0.39 were used as the substrates. The influence of growth temperature and V/III ratio on the properties of the OMVPE epilayers was studied. This resulted in the determination of an optimum growth temperature of 625 °C and an optimum V/III ratio range of 40–50. The results of the mismatch due to the different lattice constants of the GaxIn1−xP epilayer and the substrate were investigated. It was found that high-quality GaxIn1−xP epilayers can be obtained only when the mismatch ||Δa/a0|| is less than 1×10−3. Under the conditions mentioned above, epilayers were reproducibly obtained with featureless surface morphologies, and photoluminescence (PL) with high intensities and narrow half-widths (41–43 meV at 300 K). The dislocation etch pit densities ρ of Ga0.65In0.35P and Ga0.69In0.31P epilayers were 7.4–8.6×104 cm−2, grown lattice matched to GaAs1−yPy ( y=0.30, 0.39) substrates with ρ=6.4–7.5×105 cm−2. The degradation of PL intensity after annealing at temperatures between 400 and 600 °C in H2 or N2 indicates an increase in the surface recombination velocity for GaInP epilayers. Etching 30 A(ring) from the surface was found to restore the original PL intensity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337308
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