Thermally induced change in the profile of GaAs/AlGaAs quantum wells

Peyre, Hervé; Camassel, Jean; Gillin, W. P.; Homewood, K. P.; Grey, R.

doi:10.1016/0921-5107(94)90077-9

Cited by 7 publications

(16 citation statements)

References 11 publications

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“…The quantum wells we shall study were experimentally grown and investigated in [25]. We have considered this system without an applied electric field in [23] and have obtained results in good agreement with the experimental data.…”

Section: Model and Methodssupporting

confidence: 71%

“…Equation (1) is widely used in the literature (see, for instance, Ref. [25]). We use the sp 3 s * spin-dependent empirical tight-binding (ETB) model [26,27], the virtual crystal approximation and the surface Green function matching technique [28].…”

Section: Model and Methodsmentioning

confidence: 99%

“…Some authors define L D as (Dt) 1/2 [17] where D is the diffusion coefficient and t is the annealing time. We define L D = 2(Dt) 1/2 [25]. Equation (1) is widely used in the literature (see, for instance, Ref.…”

Section: Model and Methodsmentioning

confidence: 99%

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Stark effect in diffused quantum wells

Vlaev

Miteva

Contreras-Solorio

et al. 1999

Superlattices and Microstructures

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Section: Model and Methodssupporting

confidence: 71%

Section: Model and Methodsmentioning

confidence: 99%

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Stark effect in diffused quantum wells

Vlaev

Miteva

Contreras-Solorio

et al. 1999

Superlattices and Microstructures

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“…The Al x Ga 1−x As/GaAs heterostructures have non-abrupt interfaces due to unwanted diffusion of Al and Ga across the heterojunctions. These compositionally graded interfaces change the electronic and optical properties of the quantum well structures [1][2][3][4][5][6][7][8][9][10][11]. A detailed study about the diffusion influence on the quantum well electronic states allows to control and use the new features these systems display.…”

Section: Introductionmentioning

confidence: 99%

Electronic states in diffused quantum wells

Vlaev

Contreras-Solorio

1997

Journal of Applied Physics

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In the present study we calculate the energy values and the spatial distributions of the bound electronic states in some diffused quantum wells. The calculations are performed within the virtual crystal approximation, sp 3 s * spin dependent empirical tight-binding model and the surface Green function matching method. A good agreement is found between our results and experimental data obtained for AlGaAs/GaAs quantum wells with thermally induced changes in the profile at the interfaces. Our calculations show that for diffusion lengths L D =20 ÷ 100Å the transition (C3 − HH3) is not sensitive to the diffusion length, but the transitions (C1 − HH1), (C1 − LH1), (C2 − HH2) and (C2 − LH2) display large "blue shifts" as L D increases. For diffusion lengths L D =0 ÷ 20Å the transitions (C1 − HH1) and (C1 − LH1) are less sensitive to the L D changes than the (C3 − HH3) transition. The observed dependence is explained in terms of the bound states spatial distributions.

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“…This effect, however, is not related to intermixing, but to the ion implantation induced increase in the nonradiative traps in the material, and has been observed by a number of researchers previously. 7 It is well established that QWI is based on the modification of the shape of the QW by intermixing, 8 and these modifications are responsible for the observed PL peak shift, the changes to the optical absorption, and refractive index. 9 It appears from this study that the carrier capture is also affected by the QW profile.…”

Section: ͓S0003-6951͑98͒01849-x͔mentioning

confidence: 99%

Improved carrier collection in intermixed InGaAs/GaAs quantum wells

Dao

Johnston

Gál

et al. 1998

Applied Physics Letters

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We have used photoluminescence up conversion to study the carrier capture times into intermixed InGaAs/GaAs quantum wells. We have found that the capture into the intermixed wells is markedly faster than capture into the reference ͑unintermixed͒ quantum wells. The reasons for the significant reduction in the capture time is related to the shape of the intermixed quantum well. Such a reduction in the capture time is beneficial both in terms of the quantum efficiency and the frequency response of intermixed optoelectronic devices. © 1998 American Institute of Physics. ͓S0003-6951͑98͒01849-X͔Quantum well intermixing ͑QWI͒ is a method of considerable recent interest due to its wide applicability in optoelectronics. 1 QWI is based on the modification of the shape of the quantum well, and allows the post growth adjustment of several key parameters, such as the effective band gap, the optical absorption coefficient, and the refractive index. This flexibility enables the monolithic integration of optoelectronic devices, such as lasers, modulators, waveguides, amplifiers, etc. onto a single chip. 2 QWI has also been used to fabricate blueshifted 3 and multiplewavelength laser diodes, low threshold lasers, and lasers with saturable absorbers, in addition to improving the performance of high power lasers. 1 In this letter, we shall show that in addition to modifying the quantum well parameters mentioned above, QWI can also have a significant impact on the carrier capture into ͑intermixed͒ quantum wells. We shall show that in intermixed InGaAs/GaAs quantum wells, the carrier capture is faster than in similar but nonintermixed quantum wells. This efficient carrier capture can explain the relatively high quantum efficiency of intermixed light emitting devices, and may also result in improved frequency response of optoelectronic devices in general. The carrier capture times were determined from time resolved photoluminescence measurements using the photoluminescence up-conversion technique.The photoluminescence ͑PL͒ up-conversion experiments 4 were performed using a femtosecond self-mode locked Ti:sapphire laser, using a LiIO 3 nonlinear crystal. The laser was tunable between 750 and 900 nm, the pulse width was 80 fs, the repetition rate 85 MHZ, and the output power was 200 mW at ϭ780 nm. The time resolution of our system was approximately 200 fs. The optically excited carrier concentration was approximately 4ϫ10 10 carriers/cm 2 . The samples were mounted in a variable temperature, closed cycle, He cryostat, the temperature of which could be varied between 8 and 300 K. In this study we shall discuss results obtained on a number of In x Ga 1Ϫx As/GaAs quantum well ͑QW͒ samples grown by metalorganic chemical vapor deposition. Each sample contained two QWs: a 5-nm-wide In 0.15 Ga 0.85 As well and a 5-nm-wide In 0.3 Ga 0.7 As well embedded between 50-nm-thick GaAs barriers. To achieve intermixing, we used room temperature proton implantation in combination with rapid thermal annealing ͑RTA͒. Details of the implantation conditions...

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Thermally induced change in the profile of GaAs/AlGaAs quantum wells

Cited by 7 publications

References 11 publications

Stark effect in diffused quantum wells

Stark effect in diffused quantum wells

Electronic states in diffused quantum wells

Improved carrier collection in intermixed InGaAs/GaAs quantum wells

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