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S. M. Oak - One of the best experts on this subject based on the ideXlab platform.

  • Blueshift in sulfur treated gaasp algaas near surface quantum well
    Journal of Vacuum Science and Technology, 2012
    Co-Authors: Suparna Pal, S. D. Singh, S. Porwal, S. R. Barman, S W Dsouza, S. M. Oak
    Abstract:

    Large Blueshift was observed in a near-surface GaAs0.86P0.14/Al0.7Ga0.3As quantum well upon treatment with Na2S·xH2O solution. Very slow etching with simultaneous surface passivation of the quantum well was obtained using this chemical treatment. Photoreflectance (PR) spectra exhibit maximum Blueshift of 28 meV after treating the quantum well surface with Na2S·xH2O solution for 30 min (top layer thickness reduced to 10 A). The Blueshift is attributed to an increase in the confinement and/or an image charge effect due to the penetration of the wave function into vacuum. The Blueshift is accompanied by a significant reduction in the broadening parameter of the observed e1-lh1 transition in PR spectra indicating effective passivation along with an increase in the confinement.

  • Blueshift in sulfur treated GaAsP/AlGaAs near surface quantum well
    Journal of Vacuum Science & Technology A: Vacuum Surfaces and Films, 2012
    Co-Authors: Suparna Pal, S. D. Singh, S. Porwal, S. W. D'souza, S. R. Barman, S. M. Oak
    Abstract:

    Large Blueshift was observed in a near-surface GaAs0.86P0.14/Al0.7Ga0.3As quantum well upon treatment with Na2S·xH2O solution. Very slow etching with simultaneous surface passivation of the quantum well was obtained using this chemical treatment. Photoreflectance (PR) spectra exhibit maximum Blueshift of 28 meV after treating the quantum well surface with Na2S·xH2O solution for 30 min (top layer thickness reduced to 10 A). The Blueshift is attributed to an increase in the confinement and/or an image charge effect due to the penetration of the wave function into vacuum. The Blueshift is accompanied by a significant reduction in the broadening parameter of the observed e1-lh1 transition in PR spectra indicating effective passivation along with an increase in the confinement.

  • observation of electron confinement in inp gaas type ii ultrathin quantum wells
    Applied Physics Letters, 2010
    Co-Authors: S. D. Singh, V.k. Dixit, S. Porwal, Ravi Kumar, Aneesh Srivastava, Tapas Ganguli, T. K. Sharma, S. M. Oak
    Abstract:

    The issue of type-II band alignment for InP/GaAs heterostructure is addressed by means of simple layer architecture of ultrathin quantum wells (QWs). From specific signatures of the radiative recombination in type-II QWs especially the cube root dependence of Blueshift in the lowest excitonic transition energy on excitation power in photoluminescence measurements indicates that the observed luminescence is originating from spatially separated electrons and holes. Such a Blueshift is seen to increase with the QW thickness again confirming a type-II band alignment. A direct evidence of electron confinement in the conduction band of InP is provided by the capacitance voltage measurements.

  • Observation of electron confinement in InP/GaAs type-II ultrathin quantum wells
    Applied Physics Letters, 2010
    Co-Authors: S. D. Singh, V.k. Dixit, S. Porwal, Ravi Kumar, Aneesh Srivastava, Tapas Ganguli, T. K. Sharma, S. M. Oak
    Abstract:

    The issue of type-II band alignment for InP/GaAs heterostructure is addressed by means of simple layer architecture of ultrathin quantum wells (QWs). From specific signatures of the radiative recombination in type-II QWs especially the cube root dependence of Blueshift in the lowest excitonic transition energy on excitation power in photoluminescence measurements indicates that the observed luminescence is originating from spatially separated electrons and holes. Such a Blueshift is seen to increase with the QW thickness again confirming a type-II band alignment. A direct evidence of electron confinement in the conduction band of InP is provided by the capacitance voltage measurements.

S. D. Singh - One of the best experts on this subject based on the ideXlab platform.

  • Blueshift in sulfur treated gaasp algaas near surface quantum well
    Journal of Vacuum Science and Technology, 2012
    Co-Authors: Suparna Pal, S. D. Singh, S. Porwal, S. R. Barman, S W Dsouza, S. M. Oak
    Abstract:

    Large Blueshift was observed in a near-surface GaAs0.86P0.14/Al0.7Ga0.3As quantum well upon treatment with Na2S·xH2O solution. Very slow etching with simultaneous surface passivation of the quantum well was obtained using this chemical treatment. Photoreflectance (PR) spectra exhibit maximum Blueshift of 28 meV after treating the quantum well surface with Na2S·xH2O solution for 30 min (top layer thickness reduced to 10 A). The Blueshift is attributed to an increase in the confinement and/or an image charge effect due to the penetration of the wave function into vacuum. The Blueshift is accompanied by a significant reduction in the broadening parameter of the observed e1-lh1 transition in PR spectra indicating effective passivation along with an increase in the confinement.

  • Blueshift in sulfur treated GaAsP/AlGaAs near surface quantum well
    Journal of Vacuum Science & Technology A: Vacuum Surfaces and Films, 2012
    Co-Authors: Suparna Pal, S. D. Singh, S. Porwal, S. W. D'souza, S. R. Barman, S. M. Oak
    Abstract:

    Large Blueshift was observed in a near-surface GaAs0.86P0.14/Al0.7Ga0.3As quantum well upon treatment with Na2S·xH2O solution. Very slow etching with simultaneous surface passivation of the quantum well was obtained using this chemical treatment. Photoreflectance (PR) spectra exhibit maximum Blueshift of 28 meV after treating the quantum well surface with Na2S·xH2O solution for 30 min (top layer thickness reduced to 10 A). The Blueshift is attributed to an increase in the confinement and/or an image charge effect due to the penetration of the wave function into vacuum. The Blueshift is accompanied by a significant reduction in the broadening parameter of the observed e1-lh1 transition in PR spectra indicating effective passivation along with an increase in the confinement.

  • observation of electron confinement in inp gaas type ii ultrathin quantum wells
    Applied Physics Letters, 2010
    Co-Authors: S. D. Singh, V.k. Dixit, S. Porwal, Ravi Kumar, Aneesh Srivastava, Tapas Ganguli, T. K. Sharma, S. M. Oak
    Abstract:

    The issue of type-II band alignment for InP/GaAs heterostructure is addressed by means of simple layer architecture of ultrathin quantum wells (QWs). From specific signatures of the radiative recombination in type-II QWs especially the cube root dependence of Blueshift in the lowest excitonic transition energy on excitation power in photoluminescence measurements indicates that the observed luminescence is originating from spatially separated electrons and holes. Such a Blueshift is seen to increase with the QW thickness again confirming a type-II band alignment. A direct evidence of electron confinement in the conduction band of InP is provided by the capacitance voltage measurements.

  • Observation of electron confinement in InP/GaAs type-II ultrathin quantum wells
    Applied Physics Letters, 2010
    Co-Authors: S. D. Singh, V.k. Dixit, S. Porwal, Ravi Kumar, Aneesh Srivastava, Tapas Ganguli, T. K. Sharma, S. M. Oak
    Abstract:

    The issue of type-II band alignment for InP/GaAs heterostructure is addressed by means of simple layer architecture of ultrathin quantum wells (QWs). From specific signatures of the radiative recombination in type-II QWs especially the cube root dependence of Blueshift in the lowest excitonic transition energy on excitation power in photoluminescence measurements indicates that the observed luminescence is originating from spatially separated electrons and holes. Such a Blueshift is seen to increase with the QW thickness again confirming a type-II band alignment. A direct evidence of electron confinement in the conduction band of InP is provided by the capacitance voltage measurements.

S. Porwal - One of the best experts on this subject based on the ideXlab platform.

  • Blueshift in sulfur treated gaasp algaas near surface quantum well
    Journal of Vacuum Science and Technology, 2012
    Co-Authors: Suparna Pal, S. D. Singh, S. Porwal, S. R. Barman, S W Dsouza, S. M. Oak
    Abstract:

    Large Blueshift was observed in a near-surface GaAs0.86P0.14/Al0.7Ga0.3As quantum well upon treatment with Na2S·xH2O solution. Very slow etching with simultaneous surface passivation of the quantum well was obtained using this chemical treatment. Photoreflectance (PR) spectra exhibit maximum Blueshift of 28 meV after treating the quantum well surface with Na2S·xH2O solution for 30 min (top layer thickness reduced to 10 A). The Blueshift is attributed to an increase in the confinement and/or an image charge effect due to the penetration of the wave function into vacuum. The Blueshift is accompanied by a significant reduction in the broadening parameter of the observed e1-lh1 transition in PR spectra indicating effective passivation along with an increase in the confinement.

  • Blueshift in sulfur treated GaAsP/AlGaAs near surface quantum well
    Journal of Vacuum Science & Technology A: Vacuum Surfaces and Films, 2012
    Co-Authors: Suparna Pal, S. D. Singh, S. Porwal, S. W. D'souza, S. R. Barman, S. M. Oak
    Abstract:

    Large Blueshift was observed in a near-surface GaAs0.86P0.14/Al0.7Ga0.3As quantum well upon treatment with Na2S·xH2O solution. Very slow etching with simultaneous surface passivation of the quantum well was obtained using this chemical treatment. Photoreflectance (PR) spectra exhibit maximum Blueshift of 28 meV after treating the quantum well surface with Na2S·xH2O solution for 30 min (top layer thickness reduced to 10 A). The Blueshift is attributed to an increase in the confinement and/or an image charge effect due to the penetration of the wave function into vacuum. The Blueshift is accompanied by a significant reduction in the broadening parameter of the observed e1-lh1 transition in PR spectra indicating effective passivation along with an increase in the confinement.

  • observation of electron confinement in inp gaas type ii ultrathin quantum wells
    Applied Physics Letters, 2010
    Co-Authors: S. D. Singh, V.k. Dixit, S. Porwal, Ravi Kumar, Aneesh Srivastava, Tapas Ganguli, T. K. Sharma, S. M. Oak
    Abstract:

    The issue of type-II band alignment for InP/GaAs heterostructure is addressed by means of simple layer architecture of ultrathin quantum wells (QWs). From specific signatures of the radiative recombination in type-II QWs especially the cube root dependence of Blueshift in the lowest excitonic transition energy on excitation power in photoluminescence measurements indicates that the observed luminescence is originating from spatially separated electrons and holes. Such a Blueshift is seen to increase with the QW thickness again confirming a type-II band alignment. A direct evidence of electron confinement in the conduction band of InP is provided by the capacitance voltage measurements.

  • Observation of electron confinement in InP/GaAs type-II ultrathin quantum wells
    Applied Physics Letters, 2010
    Co-Authors: S. D. Singh, V.k. Dixit, S. Porwal, Ravi Kumar, Aneesh Srivastava, Tapas Ganguli, T. K. Sharma, S. M. Oak
    Abstract:

    The issue of type-II band alignment for InP/GaAs heterostructure is addressed by means of simple layer architecture of ultrathin quantum wells (QWs). From specific signatures of the radiative recombination in type-II QWs especially the cube root dependence of Blueshift in the lowest excitonic transition energy on excitation power in photoluminescence measurements indicates that the observed luminescence is originating from spatially separated electrons and holes. Such a Blueshift is seen to increase with the QW thickness again confirming a type-II band alignment. A direct evidence of electron confinement in the conduction band of InP is provided by the capacitance voltage measurements.

Atsuo Kasuya - One of the best experts on this subject based on the ideXlab platform.

  • Blueshifts in the ultraviolet absorption spectra of cerium oxide nanocrystallites
    Journal of Applied Physics, 2003
    Co-Authors: Shin Tsunekawa, Jian-tao Wang, Yoshiyuki Kawazoe, Atsuo Kasuya
    Abstract:

    Blueshifts in the ultraviolet absorption spectra have been observed in cerium oxide nanocrystallites. The mechanism of the absorption is a charge-transfer optical transition. The relationships among the Blueshift, valence state of cerium ions, and the particle size are formulated. The Blueshifts are well explained for diameters down to less than a few nanometers by the change in the electronic band structure.

  • Blueshifts in the ultraviolet absorption spectra of amphoteric SnO2-x nanocrystalline particles
    Journal of Applied Physics, 2002
    Co-Authors: Shin Tsunekawa, Junyong Kang, Katsuhiko Asami, Atsuo Kasuya
    Abstract:

    Blueshifts in the ultraviolet absorption spectra of amphoteric SnO2−x nanocrystalline particles differ greatly in acidic and alkaline sols. X-ray diffraction measurements show that the average lattice strain of the nanocrystalline particles in aqueous ammonia sols is about twice as large as that in oxalic acid sols. The size dependence of the Blueshift without lattice strain is proposed to be about three times as large as that in an alkaline sol with large strain. X-ray photoelectron spectroscopic measurements reveal that the valence of Sn in acidic and alkaline sols is not 4 but less than 3. It is strongly suggested that the Blueshift depends not only on the crystalline size but also most importantly on the lattice strain and second on the valence state of the Sn ions.

Marcos H. Degani - One of the best experts on this subject based on the ideXlab platform.

  • On the origin of the Blueshift from type-II quantum dots emission using microphotoluminescence
    Applied Physics Letters, 2002
    Co-Authors: M. K. K. Nakaema, Fernando Iikawa, M. J. S. P. Brasil, E. Ribeiro, Gilberto Medeiros-ribeiro, W. Carvalho, Marcelo Z. Maialle, Marcos H. Degani
    Abstract:

    We have studied type-II InP/GaAs self-assembled quantum dots by microphotoluminescence spectroscopy. Sharp spectral features were observed on top of a broad emission band. They are associated to statistical fluctuations from the ensemble of dots. Photoluminescence measurements as a function of the excitation intensity revealed markedly distinct behaviors: the broadband contour shows a large Blueshift while the energy positions of the sharp features remain basically constant. We show that the large Blueshift of the broad emission band in type-II quantum dots is not due to the barrier interface potential variation, but to the state filling of higher-energy states.