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  • 1
    Electronic Resource
    Electronic Resource
    Strain-induced band-gap modulation in GaAs/AlGaAs quantum-well structure using thin-film stressors (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 1763-1771 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of strain-induced band-gap modulation has been studied in a GaAs/AlGaAs multiple-quantum-well structure with the wells located at various depths in the structure. The energy change in the quantum wells was calculated based on simple elasticity theory and measured using photoluminescence on the structure where a thin-film stressor array was deposited. Metallic thin-film stressors were made by conventional thin-film deposition techniques followed by photolithography. It was found that the elasticity theory describes the energy changes reasonably well in comparison with the experimental results. For stressor layers that react with the heterojunction structure, the situation was more complex and requires more detailed analysis. Based on the calculated and experimental results it appears possible to fabricate quantum wire with lateral dimensions of less than 100 nm using thin-film technology and e-beam lithography. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360966
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  • 2
    Electronic Resource
    Electronic Resource
    Changing photoluminescence intensity from GaAs/Al0.3Ga0.7As heterostructures upon chemisorption of SO2 (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 1233-1240 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Chemisorption of SO2 gas molecules onto photowashed GaAs surfaces results in a change in the density of charge at the surface, giving rise to a measurable change in the charge distribution within the semiconductor. We consider the development of a novel semiconductor chemical sensor based on this phenomenon. The intensity of photoluminescence (PL) from metalorganic vapor phase epitaxy grown GaAs/Al0.3Ga0.7As structures at 300 K is used to detect this change in charge distribution. The doping densities and layer thicknesses within these heterostructures are shown to have a profound influence on the relative magnitude of PL intensity and its sensitivity to changes in the density of surface charge brought about by chemisorption of SO2. New analytical and finite element method (FEM) numerical models are derived to quantitatively predict the effect of changing surface charge on the PL intensity from finite thickness heterostructure layers. The PL response from these heterostructures is shown to follow the trends predicted by these models and suggests that the adsorption of SO2 from a 0.6 mol % mixture of SO2 in N2 results in a reduction in the negative surface charge density by 9×109 to 2×1010 cm−2. Simultaneous changes in surface recombination rates due to adsorption are shown (using the FEM model) to have no effect on the PL intensity from the structures studied here. The results are applied to the improvement of signal characteristics from a potential chemical sensor device. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358924
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  • 3
    Electronic Resource
    Electronic Resource
    Film stress of sputtered W/C multilayers and strain relaxation upon annealing (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 1530-1533 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Sensitive curvature measurements were performed on 40 A(ring) period W/C multilayer structures on Si substrates using a two beam laser reflection technique. A compressive stress of approximately 1530 MPa was measured in these sputtered multilayer films. Thermal annealing to 500 °C resulted in very little strain relaxation in the multilayers but x-ray diffraction data show a slight increase of the multilayer period. Significant strain relaxation, though, was observed when a 400 A(ring) W buffer layer was included. Thermal annealing of these samples to 400–500 °C resulted in large strain relaxation due to the growth of α-W crystals in the buffer layer. Large oxide formation on air annealed samples did not significantly change the strain state of the films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356390
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of microstructure on excitonic luminescence of spontaneously ordered Ga0.52In0.48P alloys (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 5418-5420 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We compare the results of low-temperature (4.2 K) microphotoluminescence (PL) measurements on cleaved edges of spontaneously ordered GaInP2 alloy samples with the results of cross-section transmission electron microscopy (TEM). The TEM dark-field images show that the size of ordered domains grows as the deposition progresses. The excitonic luminescence peak in the micro-PL spectra of GaInP2 is stronger near the surface of the thin film than near the substrate. From these results, we conclude that there is a direct correlation between the domain size or alternatively, the density of domain boundaries, and the relative strength of the excitonic peak. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367371
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  • 5
    Electronic Resource
    Electronic Resource
    Low-temperature cleaved-edge polarized-photoluminescence studies of spontaneously ordered GaInP2 alloys (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 1773-1775 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report low-temperature polarized-photoluminescence (PL) measurements on (110) cleaved edges of ordered GaInP2 alloys. By comparing the intensity of the forbidden PL polarized along the ordering axis with that of the allowed PL polarized orthogonal to the ordering axis, we study the effect of coulomb interaction on the excitonic transition rate. The experimentally obtained polarization ratios of 13–20 are consistent with calculations based on an eight-band k⋅p model. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.366898
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  • 6
    Electronic Resource
    Electronic Resource
    Spatially resolved photoluminescence in partially ordered GaInP2 (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 706-708 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Scanning confocal microscopy combined with high-resolution spectroscopy is used to probe the spatial variations in the low-temperature (5.0 K) photoluminescence (PL) of partially ordered GaInP2 with a spatial resolution of 0.7 μm. We observe large regions (1–2 μm) wherein the excitonic PL is suppressed up to a factor of four ("defect-rich" regions) when compared to unaffected areas. These defect-rich regions show a commensurate enhancement in the lower energy below gap emission. The spatial extent of this effect is inconsistent with the picture that the low-energy emission originates solely at the antiphase boundaries of the ordered domains and therefore must originate from other defects within the ordered domain as well. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123189
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  • 7
    Electronic Resource
    Electronic Resource
    Ge-related faceting and segregation during the growth of metastable (GaAs)1−x(Ge2)x alloy layers by metal–organic vapor-phase epitaxy (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 1382-1384 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: (GaAs)1−x(Ge2)x alloy layers, 0〈x〈0.22, have been grown by metal–organic vapor-phase epitaxy on vicinal (001) GaAs substrates. Transmission electron microscopy revealed pronounced phase separation in these layers, resulting in regions of GaAs-rich zinc-blende and Ge-rich diamond cubic material that appears to lead to substantial band-gap narrowing. For x=0.1 layers, the phase-separated microstructure consisted of intersecting sheets of Ge-rich material on {115}B planes surrounding cells of GaAs-rich material, with little evidence of antiphase boundaries. Atomic force microscopy revealed {115}B surface faceting associated with the phase separation. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123557
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  • 8
    Electronic Resource
    Electronic Resource
    Γ–L–X mixed symmetry of nitrogen-induced states in GaAs1−xNx probed by resonant Raman scattering (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 1297-1299 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A resonant Raman scattering study near the nitrogen-induced E+ state in GaAs1−xNx at 80 K with special emphasis on all the zone-boundary phonons is used to investigate the full symmetry of the E+ state. We have observed that various phonons at the L- and X-zone boundaries not only emerge as strong and sharp Raman features for excitations near the E+ transition but also exhibit the same intensity resonance enhancement as observed for the zone center phonons, longitudinal-optical (Γ) and transverse-optical (Γ). Our data provide strong evidence of significant L and X components in the wave function of the nitrogen-induced E+ state in GaAs1−xNx. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1399010
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  • 9
    Electronic Resource
    Electronic Resource
    Structural changes during annealing of GaInAsN (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 748-750 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The alloy GaInAsN has great potential as a lower-band-gap material lattice matched to GaAs, but there is little understanding of what causes its poor optoelectronic properties and why these improve with annealing. This study provides information about the structural changes that occur when GaInAsN is annealed. The Fourier transform infrared spectra exhibit two primary features: a triplet at ∼470 cm−1 (Ga–N stretch) and two or three bands at ∼3100 cm−1 (N–H stretch). The change in the Ga–N stretch absorption can be explained if the nitrogen environment is converted from NGa4 to NInGa3 after annealing. The N–H stretch is also changed after annealing, implying a second, and unrelated, structural change. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1345819
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  • 10
    Electronic Resource
    Electronic Resource
    BGaInAs alloys lattice matched to GaAs (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 1443-1445 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the epitaxial growth of zinc-blende BxGa1−x−yInyAs and BxGa1−xAs on GaAs substrates with boron concentrations (x) up to 2%–4% by atmospheric-pressure metalorganic chemical vapor deposition. The band gap of BxGa1−xAs increases by only 4–8 meV/%B with increasing boron concentration in this concentration range. We demonstrate an epitaxial BxGa1−x−yInyAs layer deposited on GaAs with a band gap of 1.34 eV that is significantly less strained than a corresponding Ga1−yInyAs layer with the same band gap. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126058
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