Structure and formation mechanisms of AlGaAs V-groove vertical quantum wells grown by low pressure organometallic chemical vapor deposition

Biasiol, G.; Reinhardt, F.; Gustafsson, Anders; Martinet, E.; Kapon, E.

doi:10.1063/1.117686

Cited by 41 publications

(25 citation statements)

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“…The self-limiting evolution of the bottom facets is evidenced by the perpendicular propagation of the dark vertical stripe at the center of the groove (see Fig. 2), which represents Ga segregation at the nanofacets defining the bottom of the groove (so-called vertical quantum well, VQW) [16]. On the other hand, the boundary between the top of the mesa and the sidewalls (short-dashed line in Fig.…”

Section: (Received 1 June 1998)mentioning

confidence: 98%

“…The selflimiting AlGaAs facet widths give the confinement dimension of VQW structures formed in this way on Vgrooved substrates [16,17]. The fact that the self-limiting width increases with the group-III diffusion length explains directly the self-ordering of crescent-shaped QWRs grown on V-grooves [5].…”

Section: (Received 1 June 1998)mentioning

confidence: 99%

“…Strain effects could be treated in the same framework by adding the stress term in the chemical potential in (1). This model forms the basis for understanding the self-ordering of a variety of quantum nanostructures formed by growth on nonplanar substrates, including VQWs [16], crescent shaped QWRs [5], and pyramidal QDs [7].…”

Section: (Received 1 June 1998)mentioning

confidence: 99%

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Mechanisms of Self-Ordering of Quantum Nanostructures Grown on Nonplanar Surfaces

1998

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We present an analytic model that explains the self-ordering of quantum nanostructures grown on nonplanar surfaces. Self-limiting growth in these structures results from the interplay among growthrate anisotropy, curvature-induced capillarity, and, for alloys, entropy of mixing effects. Experimental results on self-limiting organometallic chemical vapor deposition on corrugated surfaces are in quantitative agreement with the model. The implications of the self-limiting growth characteristics on the self-ordering of quantum wells, wires, and dots are discussed. [S0031-9007(98)07220-2] PACS numbers: 68.65. + g, 81.10.Bk, 82.65.Dp Two-or three-dimensionally quantum-confined semiconductor structures have attracted much attention because of their interesting physical properties and potential device applications [1]. To overcome limitations in size and interface quality related to traditional lithography techniques, many efforts have been devoted to study their formation during the epitaxial process [2]. This can be accomplished if a suitable driving force is introduced to yield the desired lateral heterostructure patterning. A widely used approach in this direction is to exploit self-ordering processes on planar surfaces, as for strained-induced Stranski-Krastanow growth of quantum dots (QDs) [3,4]. Such techniques have the advantage that self-ordering is achieved without any surface patterning prior to growth; however, they suffer from a limited control on uniformity and deposition site due to the intrinsic random nature of the nucleation process.Self-ordering of nanostructures on nonplanar surfaces has the potential for solving these problems, as the corrugated surface can provide a template for the nucleation sites. In fact, organometallic chemical vapor deposition (OMCVD) and molecular beam epitaxy (MBE) on substrates patterned with corrugations (see Fig. 1) [5,6] or with pyramidal patterns [7] have been successfully employed to fabricate uniform arrays of quantum wires (QWRs) and QDs. Despite the accurate structural control demonstrated with this approach, the understanding of the self-limiting growth mechanism on such corrugated surfaces has been essentially phenomenological [8]. Existing models can, in fact, predict only constant growth rates of thick layers on mm-sized facets, depending on their orientation and environment, as a result of gas-phase and surface diffusion [9,10]. The growth behavior of facets in the 10-nm scale, relevant to the self-ordering of quantum nanostructures, cannot be explained with such models, since facet-size dependent surface diffusion fluxes should be invoked to account for the self-limiting growth [11].In this Letter we address the self-limiting growth of a corrugated surface, and establish a model that quantitatively describes the self-ordering of quantum wells (QWs), QWRs, and QDs on such patterned substrates.The formation of surface patterns during growth relies on lateral gradients in the surface chemical potential m. Considering, for simplicity, variations in only one dim...

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Section: (Received 1 June 1998)mentioning

confidence: 98%

Section: (Received 1 June 1998)mentioning

confidence: 99%

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Mechanisms of Self-Ordering of Quantum Nanostructures Grown on Nonplanar Surfaces

1998

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“…figure 1(c), obtained by transmission electron microscopy (TEM); a crescent-shaped GaAs QWR forms at the vertex of two SQWs, separated from them by a narrow constriction or pinch-off. A vertical quantum well (VQW) also forms at the centre of the groove, perpendicular to the substrate, due to the higher mobility of Ga atoms in the AlGaAs [14].…”

Section: Methodsmentioning

confidence: 99%

Longitudinal photocurrent spectroscopy of a single GaAs/AlGaAs v-groove quantum wire

et al. 2005

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Modulation-doped GaAs v-groove quantum wires (QWRs) have been fabricated with novel electrical contacts made to two-dimensional electron-gas (2DEG) reservoirs. Here, we present longitudinal photocurrent (photoconductivity/PC) spectroscopy measurements of a single QWR. We clearly observe conductance in the ground-state one-dimensional subbands; in addition, a highly temperature-dependent response is seen from other structures within the v-groove. The latter phenomenon is attributed to the effects of structural topography and localization on carrier relaxation. The results of power-dependent PC measurements suggest that the QWR behaves as a series of weakly interacting localized states, at low temperatures.

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“…The effect of the growth conditions ͑temperature and reactor pressure͒ and Al nominal composition of the Al x Ga 1Ϫx As layer on the Ga segregation-and hence the vertical quantum well ͑VQW͒ potential depth and widthhas been studied. [2][3][4] Low-pressure ͑LP͒ ͑20 mbars͒ growth was demonstrated to yield extremely narrow ͑a few nm wide͒ multiple-VQW's with well-defined features. 4 The distribution of Al composition across the VQW was evidenced by atomic force microscopy ͑AFM͒ with a limited ͑a few nm͒ spatial resolution.…”

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confidence: 99%

Carrier quantum confinement in self-orderedAlxGa1−xAsV-groove quantum wells

et al. 1997

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Observation of quantum confined states and optical anisotropy of the interband absorption in self-ordered Al x Ga 1Ϫx As vertical quantum wells ͑VQW's͒ grown on V-grooved substrates is reported. The variation in Al composition across the VQW's was determined by parallel electron energy-loss spectroscopy. It was then employed to calculate the eigenstates of the confined carriers in these structures, with valence-band mixing included using a 4ϫ4 k•p Luttinger model. Polarized photoluminescence excitation spectra of the structure show features attributed to transitions between electron and heavy-hole or light-hole confined eigenstates, with measured energies in good agreement with the calculated ones. Polarization anisotropy associated with confined electrons and holes is evidenced by the measured spectra and explained by valence-band mixing in the ͑011͒ self-ordered quantum well.

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Structure and formation mechanisms of AlGaAs V-groove vertical quantum wells grown by low pressure organometallic chemical vapor deposition

Cited by 41 publications

References 0 publications

Mechanisms of Self-Ordering of Quantum Nanostructures Grown on Nonplanar Surfaces

Mechanisms of Self-Ordering of Quantum Nanostructures Grown on Nonplanar Surfaces

Longitudinal photocurrent spectroscopy of a single GaAs/AlGaAs v-groove quantum wire

Carrier quantum confinement in self-orderedAlxGa1−xAsV-groove quantum wells

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