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Magnus Willander - One of the best experts on this subject based on the ideXlab platform.
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theoretical study of Shallow Acceptor states under the influence of both a confinement potential and a deformation potential
Physical Review B, 1998Co-Authors: Q X Zhao, Magnus WillanderAbstract:Energy levels of the ground and the excited Shallow Acceptor states have been calculated for center-doped strain-free ${\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ quantum wells (QW's) in the presence of an external pressure and in strained ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_{y}{\mathrm{Ga}}_{1\ensuremath{-}y}\mathrm{As}$ QW's. The impurity states are calculated using a four-band effective-mass theory, in which the valence-band mixing as well as the mismatch of the band parameters and the dielectric constants between well and barrier materials have been taken into account. The Acceptor binding energies and the internal electronic transitions are calculated. The results show that an applied external pressure in ${\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ QW's or built-in strain in ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_{y}{\mathrm{Ga}}_{1\ensuremath{-}y}\mathrm{As}$ QW's strongly influences the Acceptor states. The oscillator strengths between the Acceptor ground states and the different excited $p$-like states are also calculated for the ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_{0.3}{\mathrm{Ga}}_{0.7}\mathrm{As}$ system with three different indium fractions $x.$ The results show clearly that a built-in strain strongly influences the transition energies and the relative oscillator strengths.
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theoretical calculations of Shallow Acceptor states in gaas alxga1 xas quantum wells in the presence of an external magnetic field
Physical Review B, 1994Co-Authors: Q X Zhao, P O Holtz, Alfredo Pasquarello, B Monemar, Magnus WillanderAbstract:Energy levels of ground and excited Shallow Acceptor states in the presence of an external magnetic field have been calculated for center-doped GaAs/AlxGa1-xAs quantum wells (QW's). The impurity states are calculated within a four-band effective-mass theory, in which the valence-band mixing as well as the mismatch of the band parameters and the dielectric constants between well and barrier materials have been taken into account. The g factors of the Shallow Acceptor 1s3/2 ground states and the 2P3/2 excited states are obtained for QW's with different well widths. The infrared optical transitions corresponding to the G, D, and C lines of Acceptors in bulk GaAs have also been calculated versus magnetic fields up to 16 T for the case of Acceptors confined in QW's.
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Theoretical calculations of Shallow Acceptor states in GaAs/AlxGa1-xAs quantum wells in the presence of an external magnetic field.
Physical Review B, 1994Co-Authors: Q X Zhao, P O Holtz, Alfredo Pasquarello, B Monemar, Magnus WillanderAbstract:Energy levels of ground and excited Shallow Acceptor states in the presence of an external magnetic field have been calculated for center-doped GaAs/AlxGa1-xAs quantum wells (QW's). The impurity states are calculated within a four-band effective-mass theory, in which the valence-band mixing as well as the mismatch of the band parameters and the dielectric constants between well and barrier materials have been taken into account. The g factors of the Shallow Acceptor 1s3/2 ground states and the 2P3/2 excited states are obtained for QW's with different well widths. The infrared optical transitions corresponding to the G, D, and C lines of Acceptors in bulk GaAs have also been calculated versus magnetic fields up to 16 T for the case of Acceptors confined in QW's.
Q X Zhao - One of the best experts on this subject based on the ideXlab platform.
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theoretical study of Shallow Acceptor states under the influence of both a confinement potential and a deformation potential
Physical Review B, 1998Co-Authors: Q X Zhao, Magnus WillanderAbstract:Energy levels of the ground and the excited Shallow Acceptor states have been calculated for center-doped strain-free ${\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ quantum wells (QW's) in the presence of an external pressure and in strained ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_{y}{\mathrm{Ga}}_{1\ensuremath{-}y}\mathrm{As}$ QW's. The impurity states are calculated using a four-band effective-mass theory, in which the valence-band mixing as well as the mismatch of the band parameters and the dielectric constants between well and barrier materials have been taken into account. The Acceptor binding energies and the internal electronic transitions are calculated. The results show that an applied external pressure in ${\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ QW's or built-in strain in ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_{y}{\mathrm{Ga}}_{1\ensuremath{-}y}\mathrm{As}$ QW's strongly influences the Acceptor states. The oscillator strengths between the Acceptor ground states and the different excited $p$-like states are also calculated for the ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_{0.3}{\mathrm{Ga}}_{0.7}\mathrm{As}$ system with three different indium fractions $x.$ The results show clearly that a built-in strain strongly influences the transition energies and the relative oscillator strengths.
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theoretical calculations of Shallow Acceptor states in gaas alxga1 xas quantum wells in the presence of an external magnetic field
Physical Review B, 1994Co-Authors: Q X Zhao, P O Holtz, Alfredo Pasquarello, B Monemar, Magnus WillanderAbstract:Energy levels of ground and excited Shallow Acceptor states in the presence of an external magnetic field have been calculated for center-doped GaAs/AlxGa1-xAs quantum wells (QW's). The impurity states are calculated within a four-band effective-mass theory, in which the valence-band mixing as well as the mismatch of the band parameters and the dielectric constants between well and barrier materials have been taken into account. The g factors of the Shallow Acceptor 1s3/2 ground states and the 2P3/2 excited states are obtained for QW's with different well widths. The infrared optical transitions corresponding to the G, D, and C lines of Acceptors in bulk GaAs have also been calculated versus magnetic fields up to 16 T for the case of Acceptors confined in QW's.
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Theoretical calculations of Shallow Acceptor states in GaAs/AlxGa1-xAs quantum wells in the presence of an external magnetic field.
Physical Review B, 1994Co-Authors: Q X Zhao, P O Holtz, Alfredo Pasquarello, B Monemar, Magnus WillanderAbstract:Energy levels of ground and excited Shallow Acceptor states in the presence of an external magnetic field have been calculated for center-doped GaAs/AlxGa1-xAs quantum wells (QW's). The impurity states are calculated within a four-band effective-mass theory, in which the valence-band mixing as well as the mismatch of the band parameters and the dielectric constants between well and barrier materials have been taken into account. The g factors of the Shallow Acceptor 1s3/2 ground states and the 2P3/2 excited states are obtained for QW's with different well widths. The infrared optical transitions corresponding to the G, D, and C lines of Acceptors in bulk GaAs have also been calculated versus magnetic fields up to 16 T for the case of Acceptors confined in QW's.
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the electronic structure of a Shallow Acceptor and its bound exciton confined in gaas algaas quantum wells
Journal De Physique Iv, 1993Co-Authors: P O Holtz, J.l. Merz, Q X Zhao, B Monemar, C I Harris, M Sundaram, A C GossardAbstract:The exciton bound (BE) at the Shallow Be Acceptor confined in a narrow GaAs/AlGaAs quantum well (QW) has been investigated by means of selective photoluminescence (SPL) and PL excitation (PLE) experiments. For the Shallow Acceptor, several excited states have been observed as two-hole transition (THT) satellites of the BE. The heavy hole (hh)-like excited nS(Γ 6 ) Acceptor states dominate the satellite spectrum, but also the light hole (lh)-like excited 2S(Γ 7 ) and the parity forbidden transition to the 2P 3/2 excited state have been monitored in SPL spectra. When detecting a THT satellite, the 1S(Γ 7 ) hh-like Acceptor ground state has been spectrally resolved from the 1S(Γ 6 ) hh-like state in PLE spectra. Several BE states have been theoretically predicted and observed in PLE spectra with the J=5/2 state at lowest energy, like in bulk GaAs. The proposed interpretation of the Acceptor hh- and 1h-states is confirmed by SPL and PLE experiments in the presence of an applied magnetic field and in polarized PLE measurements. An effective g-value for the Acceptor BE recombination in varying degree of confinement is derived from these Zeeman measurements
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electronic structure of a Shallow Acceptor confined in a gaas alxga1 xas quantum well
Physical Review B, 1993Co-Authors: P O Holtz, J.l. Merz, Q X Zhao, B Monemar, M Sundaram, A C GossardAbstract:The electronic structure of a Shallow neutral Acceptor and its bound exciton (BE) in GaAs/Al x Ga 1-x quantum wells has been investigated by optical spectroscopy. The heavy-hole and light-hole Acceptor ground states are both observed in photoluminescence excitation (PLE) spectra. This interpretation is supported by magnetic-field and polarization-dependent PLE experiments. The effective g value for the Acceptor BE emission varies strongly with the degree of confinement. Several BE states are theoretically predicted and observed in PLE spectra with the J=5/2 state at lowest energy, as in bulk GaAs
Alfredo Pasquarello - One of the best experts on this subject based on the ideXlab platform.
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theoretical calculations of Shallow Acceptor states in gaas alxga1 xas quantum wells in the presence of an external magnetic field
Physical Review B, 1994Co-Authors: Q X Zhao, P O Holtz, Alfredo Pasquarello, B Monemar, Magnus WillanderAbstract:Energy levels of ground and excited Shallow Acceptor states in the presence of an external magnetic field have been calculated for center-doped GaAs/AlxGa1-xAs quantum wells (QW's). The impurity states are calculated within a four-band effective-mass theory, in which the valence-band mixing as well as the mismatch of the band parameters and the dielectric constants between well and barrier materials have been taken into account. The g factors of the Shallow Acceptor 1s3/2 ground states and the 2P3/2 excited states are obtained for QW's with different well widths. The infrared optical transitions corresponding to the G, D, and C lines of Acceptors in bulk GaAs have also been calculated versus magnetic fields up to 16 T for the case of Acceptors confined in QW's.
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Theoretical calculations of Shallow Acceptor states in GaAs/AlxGa1-xAs quantum wells in the presence of an external magnetic field.
Physical Review B, 1994Co-Authors: Q X Zhao, P O Holtz, Alfredo Pasquarello, B Monemar, Magnus WillanderAbstract:Energy levels of ground and excited Shallow Acceptor states in the presence of an external magnetic field have been calculated for center-doped GaAs/AlxGa1-xAs quantum wells (QW's). The impurity states are calculated within a four-band effective-mass theory, in which the valence-band mixing as well as the mismatch of the band parameters and the dielectric constants between well and barrier materials have been taken into account. The g factors of the Shallow Acceptor 1s3/2 ground states and the 2P3/2 excited states are obtained for QW's with different well widths. The infrared optical transitions corresponding to the G, D, and C lines of Acceptors in bulk GaAs have also been calculated versus magnetic fields up to 16 T for the case of Acceptors confined in QW's.
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infrared transitions between Shallow Acceptor states in gaas ga1 xalxas quantum wells
Physical Review B, 1991Co-Authors: Samuele Fraizzoli, Alfredo PasquarelloAbstract:We calculate energies and oscillator strengths of infrared transitions between ground and excited Shallow Acceptor states in quantum wells (QW's) for varying well width. The impurity states are calculated within a four-band effective-mass theory, which accounts for the valence-band mixing as well as for the mismatch of the band parameters and the dielectric constants between well and barrier materials. The envelope function is expanded into a basis set consisting of products of two-dimensional hydrogeniclike functions and impurity-free QW eigenfunctions at k parallel-to = 0. The present method is suited for s-type ground states as well as for p-type excited states. We obtain the absorption spectra for well widths ranging from 50 to 200 angstrom. We find an overall increase of the transition energies for decreasing well widths. For polarization in the layer planes, the oscillator strengths of the lines corresponding to the bulk G and D lines maintain their oscillator strengths for decreasing well widths, whereas the lines corresponding to the bulk C line are very weak for small well widths. On the other hand, in the case of polarization along the QW axis, the oscillator strengths of the main lines decrease considerably as the well width decreases. We compare our results with absorption spectra of a recent experiment, and find a fairly good agreement.
L E Oliveira - One of the best experts on this subject based on the ideXlab platform.
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theoretical study of the density of Shallow Acceptor impurity states in quantum size gaas microcrystals
Semiconductor Science and Technology, 1999Co-Authors: C A Duque, A Montes, N Porrasmontenegro, L E OliveiraAbstract:A theoretical study of the density of states of Shallow-Acceptor impurities in cylindrically shaped GaAs low-dimensional systems is presented. The Acceptor states are described within a variational scheme in the effective-mass approximation and using an infinite confinement potential model. The density of impurity states is calculated for a homogeneous distribution of Acceptor impurities within the low-dimensional heterostructure. For dimensions of the system in which the length is much larger than the radius we obtain two well-defined peaks, associated with Acceptors either at the on-centre position or at the edge position in the low-dimensional system. In addition, we have observed the appearance in the density of impurity states of an additional peak (with low relative intensity and binding energy) associated with impurities located near to the intersection between the cylindrical surface and the top or bottom end faces of the structure. The general behaviour we observed in the density of impurity states describes reasonably well the spectral features present in experimental and theoretical data about Acceptor-related photoluminescence spectra in GaAs microcrystals, cylindrical GaAs quantum-well wires and cylindrically shaped finite-length GaAs heterostructures.
P O Holtz - One of the best experts on this subject based on the ideXlab platform.
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theoretical calculations of Shallow Acceptor states in gaas alxga1 xas quantum wells in the presence of an external magnetic field
Physical Review B, 1994Co-Authors: Q X Zhao, P O Holtz, Alfredo Pasquarello, B Monemar, Magnus WillanderAbstract:Energy levels of ground and excited Shallow Acceptor states in the presence of an external magnetic field have been calculated for center-doped GaAs/AlxGa1-xAs quantum wells (QW's). The impurity states are calculated within a four-band effective-mass theory, in which the valence-band mixing as well as the mismatch of the band parameters and the dielectric constants between well and barrier materials have been taken into account. The g factors of the Shallow Acceptor 1s3/2 ground states and the 2P3/2 excited states are obtained for QW's with different well widths. The infrared optical transitions corresponding to the G, D, and C lines of Acceptors in bulk GaAs have also been calculated versus magnetic fields up to 16 T for the case of Acceptors confined in QW's.
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Theoretical calculations of Shallow Acceptor states in GaAs/AlxGa1-xAs quantum wells in the presence of an external magnetic field.
Physical Review B, 1994Co-Authors: Q X Zhao, P O Holtz, Alfredo Pasquarello, B Monemar, Magnus WillanderAbstract:Energy levels of ground and excited Shallow Acceptor states in the presence of an external magnetic field have been calculated for center-doped GaAs/AlxGa1-xAs quantum wells (QW's). The impurity states are calculated within a four-band effective-mass theory, in which the valence-band mixing as well as the mismatch of the band parameters and the dielectric constants between well and barrier materials have been taken into account. The g factors of the Shallow Acceptor 1s3/2 ground states and the 2P3/2 excited states are obtained for QW's with different well widths. The infrared optical transitions corresponding to the G, D, and C lines of Acceptors in bulk GaAs have also been calculated versus magnetic fields up to 16 T for the case of Acceptors confined in QW's.
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the electronic structure of a Shallow Acceptor and its bound exciton confined in gaas algaas quantum wells
Journal De Physique Iv, 1993Co-Authors: P O Holtz, J.l. Merz, Q X Zhao, B Monemar, C I Harris, M Sundaram, A C GossardAbstract:The exciton bound (BE) at the Shallow Be Acceptor confined in a narrow GaAs/AlGaAs quantum well (QW) has been investigated by means of selective photoluminescence (SPL) and PL excitation (PLE) experiments. For the Shallow Acceptor, several excited states have been observed as two-hole transition (THT) satellites of the BE. The heavy hole (hh)-like excited nS(Γ 6 ) Acceptor states dominate the satellite spectrum, but also the light hole (lh)-like excited 2S(Γ 7 ) and the parity forbidden transition to the 2P 3/2 excited state have been monitored in SPL spectra. When detecting a THT satellite, the 1S(Γ 7 ) hh-like Acceptor ground state has been spectrally resolved from the 1S(Γ 6 ) hh-like state in PLE spectra. Several BE states have been theoretically predicted and observed in PLE spectra with the J=5/2 state at lowest energy, like in bulk GaAs. The proposed interpretation of the Acceptor hh- and 1h-states is confirmed by SPL and PLE experiments in the presence of an applied magnetic field and in polarized PLE measurements. An effective g-value for the Acceptor BE recombination in varying degree of confinement is derived from these Zeeman measurements
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electronic structure of a Shallow Acceptor confined in a gaas alxga1 xas quantum well
Physical Review B, 1993Co-Authors: P O Holtz, J.l. Merz, Q X Zhao, B Monemar, M Sundaram, A C GossardAbstract:The electronic structure of a Shallow neutral Acceptor and its bound exciton (BE) in GaAs/Al x Ga 1-x quantum wells has been investigated by optical spectroscopy. The heavy-hole and light-hole Acceptor ground states are both observed in photoluminescence excitation (PLE) spectra. This interpretation is supported by magnetic-field and polarization-dependent PLE experiments. The effective g value for the Acceptor BE emission varies strongly with the degree of confinement. Several BE states are theoretically predicted and observed in PLE spectra with the J=5/2 state at lowest energy, as in bulk GaAs