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H L Park - One of the best experts on this subject based on the ideXlab platform.

  • Interband Transition energies and carrier distributions of cdxzn1 xte znte quantum wires
    Journal of Applied Physics, 2009
    Co-Authors: J H You, J T Woo, Taewhan Kim, Koo Han Yoo, Hong Seok Lee, H L Park
    Abstract:

    Interband Transition energies and carrier distributions of the CdxZn1−xTe/ZnTe quantum wires (QWRs) were calculated by using a finite-difference method (FDM) taking into account shape-based strain effects. The shape of the CdxZn1−xTe/ZnTe QWRs was modeled to be approximately a half-ellipsoidal cylinder on the basis of the atomic force microscopy image. The excitonic peak energies corresponding to the ground electronic subband and the ground heavy-hole band (E1-HH1) at several temperatures, as determined from the FDM calculations taking into account strain effects, were in qualitatively reasonable agreement with those corresponding to the (E1-HH1) excitonic Transition, as determined from the temperature-dependent photoluminescence spectra.

  • dependence of the Interband Transition and the activation energy on the znte spacer thickness in cdte znte double quantum dots
    Solid State Communications, 2004
    Co-Authors: Jooseok Song, H L Park, T W Kim
    Abstract:

    Abstract Photoluminescence (PL) measurements were carried out to investigate the Interband Transition and the activation energy in CdTe/ZnTe double quantum dots (QDs). While the excitonic peaks corresponding to the Interband Transition from the ground electronic subband to the ground heavy-hole (E1–HH1) in the CdTe/ZnTe double QDs shifted to higher energy with decreasing ZnTe spacer thickness from 30 to 10 nm due to transformation from CdTe QDs to CdxZn1−xTe QDs, the peaks of the (E1–HH1) Transitions shifted to lower energy with decreasing spacer thickness from 10 to 3 nm due to the tunneling effects of the electrons between CdTe double QDs. The decrease in the activation energy with decreasing ZnTe spacer thickness might originate from an increase in the number of defects in the ZnTe spacer. The present results can help improve the understanding of the Interband Transition and the activation energy in CdTe/ZnTe double QDs.

  • type ii Interband Transition of zns0 78te0 22 znte single quantum wells
    Applied Physics Letters, 2004
    Co-Authors: Jae Ho Bahng, S J Moon, Kyuyeon Lee, Jonghyeon Choi, Kwangho Jeong, H L Park
    Abstract:

    Optical properties of ZnS0.78Te0.22/ZnTe single quantum wells grown on GaAs (100) substrates by hot wall epitaxy technique with varying the ZnS0.78Te0.22 well width from 0.3 to 1.8 nm were investigated by photoluminescence (PL) measurements at low temperature and by temperature-dependent PL measurements. PL results show the evidence of type-II Transition and their peak energy shifts to higher energies as the ZnS0.78Te0.22 well width decreases. In addition, temperature-dependent PL measurements show the increase of the activation energy as the well thickness decreases, indicating the increase of confinement effect. This study makes it possible to introduce proper band diagram for this structure, and can give very useful information on their device applications.

  • structural property and Interband Transition studies on cdxzn1 xte znte coupled step and rectangular quantum wells
    Journal of Crystal Growth, 1999
    Co-Authors: T W Kim, H L Park, Joungsik Kim, J Y Lee
    Abstract:

    Abstract Transmission electron microscopy (TEM) and photoluminescence (PL) measurements have been performed to investigate the structural properties and the excitonic Transitions on CdxZn1−xTe/ZnTe coupled step and rectangular quantum wells grown by double-well temperature-gradient vapor-transport deposition. High-resolution TEM measurements on the coupled step and rectangular quantum wells show that a 50 A Cd0.08Zn0.92Te shallow and a 50 A Cd0.26Zn0.74Te deep step well and a 100 A Cd0.08Zn0.92Te rectangular quantum well bounded by two ZnTe barriers are separated by a 30 A ZnTe embedded potential barrier. A PL spectrum measured at 15 K shows the dominant excitonic Transition from the ground state electronic subband to the ground state heavy-hole subband (E1–HH1). The excitonic Transition energy corresponding to the (E1–HH1) in the coupled step and rectangular quantum wells is affected by the existence of the 100 A Cd0.08Zn0.92Te rectangular quantum well. The electronic subband energies and energy wave functions in the CdxZn1−xTe asymmetric coupled quantum wells are calculated by a transfer matrix method which takes into account the strain effects. The calculated Interband Transition values are in reasonable agreement with those obtained from the PL measurements. These results can help improve understanding of the electronic structure of the complicated CdxZn1−xTe/ZnTe coupled step and rectangular quantum wells. Furthermore, these CdxZn1−xTe/ZnTe asymmetric coupled quantum wells might hold promise for the new kinds of optoelectronic devices in the blue–green region of the spectrum.

  • Interband Transition studies on cdxzn1 xte znte step quantum wells under applied electric fields
    Applied Physics Letters, 1998
    Co-Authors: T W Kim, K H Lee, H L Park
    Abstract:

    Photoluminescence (PL) measurements were carried out to investigate the Interband Transitions in CdxZn1−xTe/ZnTe asymmetric step quantum wells with and without an applied electric field. Transmission electron microscopy showed that the CdxZn1−xTe/ZnTe step quantum wells consisted of a shallow Cd0.1Zn0.9Te well and a deep Cd0.18Zn0.82Te well bound by two thick ZnTe barriers. The results for the PL data at 300 K for several applied electric fields showed that the excitonic Transition from the first electronic state to the first heavy-hole state shifted to the larger energy side as the applied electric field increased. The electronic subband energies and the wave functions in the step quantum wells were calculated by an envelope-function approximation method, taking into account the strain effects, and the calculated values of the Interband Transitions were in qualitative agreement with those obtained from the PL measurements. The Stark shift of the step quantum well was much more sensitive to the applied el...

Xingxu Yan - One of the best experts on this subject based on the ideXlab platform.

  • anomalous linear layer dependent blue shift of ultraviolet range Interband Transition in two dimensional mos2
    Journal of Physical Chemistry C, 2020
    Co-Authors: Xingxu Yan, Feng Xue, Chaitanya Gadre, Jingying Zheng, Lin Xie, Yi Zhang, Zhe Wang, Mian Zhang
    Abstract:

    The unique electronic structure of two-dimensional materials paves the way for abundant cutting-edge applications, including electronic devices and optoelectronic devices. The bandgap excitations a...

  • anomalous linear layer dependent blue shift of ultraviolet range Interband Transition in two dimensional mos
    The Journal of Physical Chemistry, 2019
    Co-Authors: Xingxu Yan, Feng Xue, Chaitanya Gadre, Z M Wang, Jingying Zheng, Lin Xie, Yi Zhang, Mian Zhang, Liying Jiao, Peng Wang
    Abstract:

    The unique electronic structure of two-dimensional materials paves the way for abundant cutting-edge applications, including electronic devices and optoelectronic devices. The bandgap excitations are nonlinearly red-shifted with the increasing layer number, leading to an intriguing tunable photon response in the visible-light range. However, there is a lack of systematic studies on the dielectric response of two-dimensional materials in the ultraviolet range. Here, we report an anomalous linear layer-dependent blue shift of the Interband Transition with a slope of 18.6 ± 1.0 meV/layer in the ultraviolet range on freestanding MoS₂ by valence-electron energy-loss spectroscopy. Such a method can provide nanometer spatial resolution, far superior to that of traditional optical methods. First-principles calculations reveal that the blue shift of the Interband Transition is due to the change of the second band below the Fermi level around the Γ point induced by the increased interlayer van der Waals interaction. The tunable Interband Transition has a potential application for modulating ultraviolet-light devices.

T W Kim - One of the best experts on this subject based on the ideXlab platform.

  • effect of inxga1 xas strain release layers on the microstructural and Interband Transition properties of inas gaas quantum dots
    Journal of Crystal Growth, 2005
    Co-Authors: J G Lim, Young Ju Park, T W Kim, Youngtae Park, J D Song, W J Choi, Ilki Han, Woonjo Cho, J I Lee, Hyung Seok Kim
    Abstract:

    Abstract The effect of In x Ga 1− x As ( x = 0.1 , 0.2) asymmetric strain release layers (ASRLs) on the microstructural and the Interband Transition properties of InAs/GaAs quantum dots (QDs) grown by using molecular beam epitaxy (MBE) and atomic layer epitaxy was investigated by using high-resolution transmission electron microscopy (HRTEM) and photoluminescence (PL) measurements. When the thickness of the ASRL covering the QDs was increased in the range between 0 and 5 nm, the PL peak corresponding to the Interband Transitions shifted to longer wavelengths due to strain relaxation. However, when the thickness of the ASRL was increased above approximately 7 nm, the peak shifted to shorter wavelengths due to the local interdiffusion of In and Ga atoms between the In x Ga 1− x As capping layer and the InAs QDs as a result of the localized strains in the In x Ga 1− x As capping layer and the InAs QDs. These results provide important information on the tunable feasibility of the Interband Transitions in the InAs/GaAs QDs utilizing the In x Ga 1− x As capping layer.

  • dependence of the Interband Transition and the activation energy on the znte spacer thickness in cdte znte double quantum dots
    Solid State Communications, 2004
    Co-Authors: Jooseok Song, H L Park, T W Kim
    Abstract:

    Abstract Photoluminescence (PL) measurements were carried out to investigate the Interband Transition and the activation energy in CdTe/ZnTe double quantum dots (QDs). While the excitonic peaks corresponding to the Interband Transition from the ground electronic subband to the ground heavy-hole (E1–HH1) in the CdTe/ZnTe double QDs shifted to higher energy with decreasing ZnTe spacer thickness from 30 to 10 nm due to transformation from CdTe QDs to CdxZn1−xTe QDs, the peaks of the (E1–HH1) Transitions shifted to lower energy with decreasing spacer thickness from 10 to 3 nm due to the tunneling effects of the electrons between CdTe double QDs. The decrease in the activation energy with decreasing ZnTe spacer thickness might originate from an increase in the number of defects in the ZnTe spacer. The present results can help improve the understanding of the Interband Transition and the activation energy in CdTe/ZnTe double QDs.

  • structural property and Interband Transition studies on cdxzn1 xte znte coupled step and rectangular quantum wells
    Journal of Crystal Growth, 1999
    Co-Authors: T W Kim, H L Park, Joungsik Kim, J Y Lee
    Abstract:

    Abstract Transmission electron microscopy (TEM) and photoluminescence (PL) measurements have been performed to investigate the structural properties and the excitonic Transitions on CdxZn1−xTe/ZnTe coupled step and rectangular quantum wells grown by double-well temperature-gradient vapor-transport deposition. High-resolution TEM measurements on the coupled step and rectangular quantum wells show that a 50 A Cd0.08Zn0.92Te shallow and a 50 A Cd0.26Zn0.74Te deep step well and a 100 A Cd0.08Zn0.92Te rectangular quantum well bounded by two ZnTe barriers are separated by a 30 A ZnTe embedded potential barrier. A PL spectrum measured at 15 K shows the dominant excitonic Transition from the ground state electronic subband to the ground state heavy-hole subband (E1–HH1). The excitonic Transition energy corresponding to the (E1–HH1) in the coupled step and rectangular quantum wells is affected by the existence of the 100 A Cd0.08Zn0.92Te rectangular quantum well. The electronic subband energies and energy wave functions in the CdxZn1−xTe asymmetric coupled quantum wells are calculated by a transfer matrix method which takes into account the strain effects. The calculated Interband Transition values are in reasonable agreement with those obtained from the PL measurements. These results can help improve understanding of the electronic structure of the complicated CdxZn1−xTe/ZnTe coupled step and rectangular quantum wells. Furthermore, these CdxZn1−xTe/ZnTe asymmetric coupled quantum wells might hold promise for the new kinds of optoelectronic devices in the blue–green region of the spectrum.

  • Interband Transition studies on cdxzn1 xte znte step quantum wells under applied electric fields
    Applied Physics Letters, 1998
    Co-Authors: T W Kim, K H Lee, H L Park
    Abstract:

    Photoluminescence (PL) measurements were carried out to investigate the Interband Transitions in CdxZn1−xTe/ZnTe asymmetric step quantum wells with and without an applied electric field. Transmission electron microscopy showed that the CdxZn1−xTe/ZnTe step quantum wells consisted of a shallow Cd0.1Zn0.9Te well and a deep Cd0.18Zn0.82Te well bound by two thick ZnTe barriers. The results for the PL data at 300 K for several applied electric fields showed that the excitonic Transition from the first electronic state to the first heavy-hole state shifted to the larger energy side as the applied electric field increased. The electronic subband energies and the wave functions in the step quantum wells were calculated by an envelope-function approximation method, taking into account the strain effects, and the calculated values of the Interband Transitions were in qualitative agreement with those obtained from the PL measurements. The Stark shift of the step quantum well was much more sensitive to the applied el...

Mian Zhang - One of the best experts on this subject based on the ideXlab platform.

  • anomalous linear layer dependent blue shift of ultraviolet range Interband Transition in two dimensional mos2
    Journal of Physical Chemistry C, 2020
    Co-Authors: Xingxu Yan, Feng Xue, Chaitanya Gadre, Jingying Zheng, Lin Xie, Yi Zhang, Zhe Wang, Mian Zhang
    Abstract:

    The unique electronic structure of two-dimensional materials paves the way for abundant cutting-edge applications, including electronic devices and optoelectronic devices. The bandgap excitations a...

  • anomalous linear layer dependent blue shift of ultraviolet range Interband Transition in two dimensional mos
    The Journal of Physical Chemistry, 2019
    Co-Authors: Xingxu Yan, Feng Xue, Chaitanya Gadre, Z M Wang, Jingying Zheng, Lin Xie, Yi Zhang, Mian Zhang, Liying Jiao, Peng Wang
    Abstract:

    The unique electronic structure of two-dimensional materials paves the way for abundant cutting-edge applications, including electronic devices and optoelectronic devices. The bandgap excitations are nonlinearly red-shifted with the increasing layer number, leading to an intriguing tunable photon response in the visible-light range. However, there is a lack of systematic studies on the dielectric response of two-dimensional materials in the ultraviolet range. Here, we report an anomalous linear layer-dependent blue shift of the Interband Transition with a slope of 18.6 ± 1.0 meV/layer in the ultraviolet range on freestanding MoS₂ by valence-electron energy-loss spectroscopy. Such a method can provide nanometer spatial resolution, far superior to that of traditional optical methods. First-principles calculations reveal that the blue shift of the Interband Transition is due to the change of the second band below the Fermi level around the Γ point induced by the increased interlayer van der Waals interaction. The tunable Interband Transition has a potential application for modulating ultraviolet-light devices.

Feng Xue - One of the best experts on this subject based on the ideXlab platform.

  • anomalous linear layer dependent blue shift of ultraviolet range Interband Transition in two dimensional mos2
    Journal of Physical Chemistry C, 2020
    Co-Authors: Xingxu Yan, Feng Xue, Chaitanya Gadre, Jingying Zheng, Lin Xie, Yi Zhang, Zhe Wang, Mian Zhang
    Abstract:

    The unique electronic structure of two-dimensional materials paves the way for abundant cutting-edge applications, including electronic devices and optoelectronic devices. The bandgap excitations a...

  • anomalous linear layer dependent blue shift of ultraviolet range Interband Transition in two dimensional mos
    The Journal of Physical Chemistry, 2019
    Co-Authors: Xingxu Yan, Feng Xue, Chaitanya Gadre, Z M Wang, Jingying Zheng, Lin Xie, Yi Zhang, Mian Zhang, Liying Jiao, Peng Wang
    Abstract:

    The unique electronic structure of two-dimensional materials paves the way for abundant cutting-edge applications, including electronic devices and optoelectronic devices. The bandgap excitations are nonlinearly red-shifted with the increasing layer number, leading to an intriguing tunable photon response in the visible-light range. However, there is a lack of systematic studies on the dielectric response of two-dimensional materials in the ultraviolet range. Here, we report an anomalous linear layer-dependent blue shift of the Interband Transition with a slope of 18.6 ± 1.0 meV/layer in the ultraviolet range on freestanding MoS₂ by valence-electron energy-loss spectroscopy. Such a method can provide nanometer spatial resolution, far superior to that of traditional optical methods. First-principles calculations reveal that the blue shift of the Interband Transition is due to the change of the second band below the Fermi level around the Γ point induced by the increased interlayer van der Waals interaction. The tunable Interband Transition has a potential application for modulating ultraviolet-light devices.