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  • 1
    Electronic Resource
    Electronic Resource
    Dynamics of laser sputtering at GaN, GaP, and GaAs surfaces (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 3268-3274 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Laser sputtering of GaAs, GaP, and GaN has been studied by measuring angle-resolved time-of-flight (TOF) distributions of emitted neutral particles. The observed mean translational energy and sputtering yield were found to show strong forward peaking depending on the laser power densities, thence on the desorption yield. This fact can be explained in terms of postdesorption collisions among desorbed particles as predicted theoretically [I. NoorBatcha, R. R. Lucchese, and Y. Zeiri, J. Chem. Phys. 86, 5816 (1987); 898, 5251 (1988), and Kelly and R. W. Dreyfus, Surf Sci. 198, 263 (1988); Nucl. Instr. Methods B 32, 341 (1988); J. Chem. Phys. 92, 5048 (1990)]. However, the observed velocity distributions of sputtered particles were found to be in contradiction with the so-called shifted Maxwellian, because the best-fitted center of mass velocities for Ga were always found to be negative. In addition, Kelly's Mach number M, estimated from the energy spectra, was found to be significantly larger than those estimated from the yield spectra. It is suggested that energy transfer from the internal states of diatomic molecules to the translational motion of Ga may play an important role in the final TOF spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350348
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  • 2
    Electronic Resource
    Electronic Resource
    Piezoelectric Franz–Keldysh effect in strained GaInN/GaN heterostructures (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 3786-3791 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pseudomorphic Ga1−xInxN/GaN single heterostructures in the composition range 0〈x〈0.2 have been investigated by photoreflectance and photoluminescence spectroscopy. Strong Franz–Keldysh oscillations near the band gap of the ternary film are observed and attributed to a large constant piezoelectric field of up to 0.63 MV/cm. This allows an accurate determination of the electric field. A significant redshift between the optical band gap from photoreflectance and the luminescence maximum is observed. Luminescence is proposed to originate in the indirect transitions between the electric field tilted band edges in GaInN. The presence of this field is expected to dominate the bandstructure and the recombination and transport processes in strained nitride structures. We find no evidence for large inhomogeneities or phase separation in this material. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369749
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  • 3
    Electronic Resource
    Electronic Resource
    Optical band gap in Ga1−xInxN (0〈x〈0.2) on GaN by photoreflection spectroscopy (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 1994-1996 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optical band gap in 40 nm Ga1−xInxN/GaN single heterostructures is investigated in the composition range 0〈x〈0.2 by photoreflection spectroscopy (PR) at room temperature and compared with photoluminescence (PL) data. Clear PR oscillations at the GaInN band gap are observed as originating in the large piezoelectric field. Effective band gap bowing parameters b are derived for pseudomorphically stressed GaInN on GaN: b=2.6 eV (PR) and b=3.2 eV (PL in localized states). Using experimental deformation potentials of GaN, b=3.8 eV is extrapolated for the optical band gap in relaxed GaInN material. Previously reported smaller values are discussed. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122346
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  • 4
    Electronic Resource
    Electronic Resource
    Intrinsic optical properties of GaN epilayers grown on SiC substrates: Effect of the built-in strain (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 1255-1257 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Intrinsic excitonic properties of GaN/SiC epilayers are studied by photoluminescence and reflectance spectroscopies. The residual built-in tensional biaxial strain, induced by the SiC substrate, is suggested to be responsible for the observed downshift of the excitonic band gap and the reduced valence band splitting in comparison with bulk strain-free GaN samples. By comparing the temperature dependence of the free exciton transition energies for bulk GaN, GaN/SiC, and GaN/Al2O3 samples, residual stress is shown to affect the temperature dependence of the excitonic band-gap energy. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117429
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  • 5
    Electronic Resource
    Electronic Resource
    High-resolution x-ray analysis of InGaN/GaN superlattices grown on sapphire substrates with GaN layers (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 3390-3392 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: InGaN/GaN superlattice structures grown on (0001) sapphire substrates with GaN layers were investigated by two-dimensional reciprocal space mapping of high-resolution x-ray diffraction. The results show that InGaN/GaN multi-quantum wells with fairly good crystallinity can be grown coherently on partially relaxed GaN layer irrespective of the large lattice mismatch and thermal incompatibility with the underlying substrate. Narrow and bright band edge related emissions were observed by photoluminescence measurements, indicating high quality of these InGaN/GaN superlattice structures. Our results suggest a larger band-gap bowing coefficient than the value reported in the literature. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117269
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  • 6
    Electronic Resource
    Electronic Resource
    Spatially resolved photoluminescence and Raman scattering experiments on the GaN/substrate interface (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 1265-1266 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present results from spatially resolved photoluminescence and Raman experiments on the substrate interface region of wurtzite GaN layers. We show that the broad photoluminescence band with an intensity maximum at 2.4 eV is not an intrinsic property of GaN. We found that this photoluminescence band is strong only near the interface. Our investigations reveal that both the substrate interface and a region of structural reorientation of the layer near the interface act as a source of the photoluminescence. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.115947
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  • 7
    Electronic Resource
    Electronic Resource
    Resonant Raman scattering in hexagonal GaN (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 2404-2406 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We performed resonant Raman scattering in hexagonal GaN using discrete laser lines in the violet and UV spectral range for optical excitation. To tune the energetic position of the fundamental gap E0 of GaN relative to the exciting photon energy the sample temperature was varied between 77 and 870 K. Analyzing both Stokes and anti-Stokes Raman spectra, the resonance profiles for Fröhlich-induced one-E1(LO) and two-E1(LO) phonon scattering could be deduced, covering the energy range from 0.5 eV below the E0 gap up to the gap energy. The strength of deformation-potential scattering by the A1(TO) mode was used as an internal reference. For excitation slightly above the E0 gap energy E1(LO) multiphonon scattering up to the fourth order was observed, which reflects the stronger polarity of the Ga-N bond as compared to conventional III-V semiconductors. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116148
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  • 8
    Electronic Resource
    Electronic Resource
    Photoluminescence of residual transition metal impurities in GaN (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 1140-1142 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A large number of epitaxial GaN samples as well as AlN ceramics have been studied by photoluminescence (PL) and PL excitation spectroscopy. In addition to the PL of residual iron, two new bands with zero-phonon-lines at 0.931 and 1.193 eV have been observed frequently in GaN. An analysis of the PL bands indicates that they arise from internal transitions within the 3d shell of residual vanadium and chromium impurities. The chromium PL has also been observed in polycrystalline AlN ceramics. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114987
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  • 9
    Electronic Resource
    Electronic Resource
    p-type conduction in Mg-doped GaN and Al0.08Ga0.92N grown by metalorganic vapor phase epitaxy (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 593-594 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Temperature dependences of the hole concentration and Hall mobility in Mg-doped GaN and Al0.08Ga0.92N grown by metalorganic vapor phase epitaxy were measured by the van der Pauw method over a wide temperature range from 100 to 500 K. Assuming that the effective mass of holes in Al0.08Ga0.92N is equal to that of GaN, the activation energy of the Mg shallow acceptor in Al0.08Ga0.92N is estimated to be about 35 meV deeper than that in GaN.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112309
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  • 10
    Electronic Resource
    Electronic Resource
    Room-temperature violet stimulated emission from optically pumped AlGaN/GaInN double heterostructure (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 1377-1379 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An AlGaN/GaInN heterostructure has been fabricated by metalorganic vapor phase epitaxy. We observed room-temperature (RT) violet stimulated emission from an optically pumped double heterostructure (DH) using GaInN as an active layer. The peak wavelength of the stimulated emission at RT from Al0.17Ga0.83N/Ga0.91In0.09N DH is 402.5 nm, and the threshold of excitation power density is about 0.13 MW/cm2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111942
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