Nature of the lowest electron states in short period GaAs-AlAs superlattices of type II

Scalbert, D.; Cernogora, J.; Guillaume, C. Benoît à la; Maaref, M.A.; Charfi, F. F.; Planel, R.

doi:10.1016/0038-1098(89)90634-0

Cited by 77 publications

(28 citation statements)

References 12 publications

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“…Using envelope-function calculations, the energy difference d = -E, between X x , y and X, states in unstrained SL was computed. The strain produces a splitting do % 19 meV, an experimental value deduced from a systematic study of time-resolved photoluminescence on a large number of samples widely distributed in region I1 [5,6]. This value is close to the estimate resulting from the known mismatch and assuming a value of the deformation potential for X-valley splitting analogous to that of GaP [7].…”

Section: Introductionmentioning

confidence: 54%

Recombination Processes in Short‐Period GaAsAlAs Superlattices of Type II

Maaref

Charfi

Scalbert

et al. 1992

Physica Status Solidi (b)

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An extensive study of time-resolved photoluminescence is made in the temperature range 1.8 to 50 K on nine samples of type-I1 GaAs-A1As (001) superlattices. In previous publications, the region is identified where the states derived from X, valleys are lower than those derived from X,, valleys, in agreement with a simple model involving the competition between X-type valley anisotropy and X valleys splitting caused by the small lattice mismatch between AlAs and GaAs. An analysis is given of the luminescence processes and of their evolution with temperature, as a function of AlAs and GdAs layer thicknesses. Excitons localized by interface roughness are found to decay through radiative processes at low temperature. A model of thermal excitation from the tail of localized exciton states is introduced, which helps to identify the pertinent parameters of temperature behaviour in these samples.On presente une etude de la photoluminescence resolue en temps de neuf echantillons de superreseaux GaAs/AlAs (001) de type I1 dans l'intervalle de temperature 1,8 a 50 K. Dans une publication prkcedente, nous avions identifie la region ou les etats derives de la vallee X, sont plus bas que ceux issus de vallees X,,, d'aprks un modele invoquant la competition entre l'effet de I'anisotropie de masse des vallees X et l'eclatement de ces memes vallees d t au petit desaccord de maille entre GaAs et AlAs. On presente une analyse des processus de luminescence et de leur evolution avec la temperature, en fonction des epaisseurs des couches de GaAs et dA1As. On trouve que le declin des excitons localisks par la rugosite d'interface est domine par les processus radiatifs B basse temperature. On propose un modele d'excitation thermique i partir d'une queue d'etats localists, qui met en evidence les parametres pertinents du comportement en temperature de ces echantillons.

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Section: Introductionmentioning

confidence: 54%

Recombination Processes in Short‐Period GaAsAlAs Superlattices of Type II

Maaref

Charfi

Scalbert

et al. 1992

Physica Status Solidi (b)

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“…This PL is generally weaker than in type I SPS, which may be understood, since it is governed by the weak overlap of envelope functions. Actually, radiative lifetimes as long as hundreds of ms have been measured for this luminescence, with strong dependence on the SPS parameters and on the observed transition [15,20,21].…”

Section: Electronic Properties: Experimental Studiesmentioning

confidence: 91%

“…The effects of this mismatch are generally neglected in the GaAs/AIAs system. Despite the poor knowledge of most bulk AlAs parameters, it was possible to estimate the initial splitting between 15 and 20 meV with ground state of Χx ,y symmetry [14,15]. As a consequence, we may now distinguish two types of "indirect" GaAs/AIAs SPS:…”

Section: Expressed As the Ratio Qco F T H E C O N D U C T I O N O F Fmentioning

confidence: 99%

“…The question of detailed symmetry of the conduction Χ states which appear in type II SPS luminescence has been investigated, with the help of uniaxial strain perturbation [14,30], time-resolved spectroscopy [15,[20][21], and optically detected magnetic resonance [25]. Although the analysis of results is intricate, the situation seems now rather clear: The two situations described above reveal at first glance in the steady-state PL spectra, provided the samples are of good quality and the exciting power is low enough to avoid high density effects (which are favoured by the very long carrier lifetimes).…”

Section: Electronic Properties: Experimental Studiesmentioning

confidence: 99%

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Physics of GaAs/AlAs Superlattices

Planel

1991

Acta Phys. Pol. A

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“…It may be viewed as a type-II quantum well, embedded into a Ga0.65Al0.35Αs layer acting as a barrier for Γ-or X-electrons. The electron ground level is of Xxy symmetry [10] and located in the AlAs layer, whereas the hole ground state is of Γ symmetry and located in the GaAs layer. The Γ-symmetry conduction level located in the GaAs layer is about 60 meV.…”

mentioning

confidence: 99%

Optical Bistability Due to Photo-Induced Charge Transfer in a Type-II GaAs/AlAs Quantum Well

Teissier¹,

Planel²

1992

Acta Phys. Pol. A

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We present a bistability of low temperature photoluminescence in a n-i-n type-II GaAs/AlAs quantum heterostructure. Spectral analysis and electrical measurements indicate that the two states correspond to hole accumulation in different layers. The transition occurs with the alignment of electronic Γ and Χ states due to optical pumping, and no external voltage bias is needed.PACS numbers: 78.55. Cr, 42.65.Ρc, 72.20.7v The feasibility of type-ΙΙ GaAs/AlAs heterostructures involving X-point conduction states has motivated several studies since 1986 [1][2][3]. In an asymmetric stucture, the creation of internal electric fields due to spatial separation of charges has been demonstrated [4]. We describe here a type-II quantum well stucture which exhibits an intrinsic optical bistability on photoluminescence (PL). The most outstanding point is that, because of photocreated electric fields, it is observable without any external voltage bias, contrary to all other electrooptic bistable devices like self electrooptic effect devices (SEED) [5], double-barrier resonant-tunnelling stuctures [6] or asymmetric quantum wells [7][8][9]. However, electrical detection and switchings are also possible.The stucture grown by molecular beam epitaxy consists of a n-i-n sequence. The intrinsic region is made of four layers, as described and labelled in Fig. 1. It may be viewed as a type-II quantum well, embedded into a Ga0.65Al0.35Αs layer acting as a barrier for Γ-or X-electrons. The electron ground level is of Xxy symmetry [10] and located in the AlAs layer, whereas the hole ground state is of Γ symmetry and located in the GaAs layer. The Γ-symmetry conduction level located in the GaAs layer is about 60 meV. above the Χ ground state. For electrical measurements under optical excitation, we have made 300 x 300 µm mesa-type diodes with a peripheric Au-Ge-Ni ohmic contact by conventional lithography and chemical etching.The PL spectra, obtained with an Argon-laser excitation, show two main lines (Fig. 2): the one (at about 1.80 eV) is attributed to recombination in the type-II well, the other (at about 2.00 eV) to recombination in the GaAlAs barriers. When the n-i-n diode is short-circuited (either by the external contacts in (656)

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Nature of the lowest electron states in short period GaAs-AlAs superlattices of type II

Cited by 77 publications

References 12 publications

Recombination Processes in Short‐Period GaAsAlAs Superlattices of Type II

Recombination Processes in Short‐Period GaAsAlAs Superlattices of Type II

Physics of GaAs/AlAs Superlattices

Optical Bistability Due to Photo-Induced Charge Transfer in a Type-II GaAs/AlAs Quantum Well

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