Bandstructures of conical quantum dots with wetting layers

Melnik, Roderick V. N.; Willatzen, Morten

doi:10.1088/0957-4484/15/1/001

Cited by 117 publications

(71 citation statements)

References 22 publications

(33 reference statements)

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“…Following the ideas of Ref. 16 we simplify the QD geometry by considering a single, conical dot atop a wetting layer of the same material and embedded in a different bulk material. The model is shown in Fig.…”

Section: A Mathematical Modelmentioning

confidence: 99%

“…16 In calculating the Fermi function in Eq. ͑13͒ we have assumed a constant WL carrier density n =10 11 cm −2 .…”

Section: A Capture Time Calculationsmentioning

confidence: 99%

“…The parameters characterizing the geometry are R 0 = 400 nm, L z = 60 nm and the ratio of dot base radius to height is kept constant at r 0 / h = 4.62 as in Ref. 16. We have carried out calculations for WL thicknesses of d = 2 nm and d = 4 nm, corresponding to Refs.…”

Section: A Capture Time Calculationsmentioning

confidence: 99%

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Influence of wetting-layer wave functions on phonon-mediated carrier capture into self-assembled quantum dots

et al. 2006

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Models of carrier dynamics in quantum dots rely strongly on adequate descriptions of the carrier wave functions. In this work we numerically solve the one-band effective mass Schrödinger equation to calculate the capture times of phonon-mediated carrier capture into self-assembled quantum dots. Comparing with results obtained using approximate carrier wave functions, we demonstrate that the capture times are strongly influenced by properties of the wetting layer wave functions not accounted for by earlier theoretical analyses.

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Section: A Mathematical Modelmentioning

confidence: 99%

“…16 In calculating the Fermi function in Eq. ͑13͒ we have assumed a constant WL carrier density n =10 11 cm −2 .…”

Section: A Capture Time Calculationsmentioning

confidence: 99%

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Influence of wetting-layer wave functions on phonon-mediated carrier capture into self-assembled quantum dots

et al. 2006

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“…To solve this problem analytically, we consider several assumptions, i.e., we deem the potential outside of the QD to be infinite, although in reality, the wavefunctions penetrate into the host material [10] . In the effective mass approximation, the Schrödinger equation for an electron inside the cone is…”

mentioning

confidence: 99%

Exact investigation of the electronic structure and the linear and nonlinear optical properties of conical quantum dots

Dezhkam

Zakery

2012

中国光学快报

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Intersubband linear and third-order nonlinear optical properties of conical quantum dots with infinite barrier potential are studied. The electronic structure of conical quantum dots through effective mass approximation is determined analytically. Linear, nonlinear, and total absorption coefficients, as well as the refractive indices of GaAs conical dots, are calculated. The effects of the size of the dots and of the incident electromagnetic field are investigated. Results show that the total absorption coefficient and the refractive index of the dots largely depend on the size of the dots and on the intensity and polarization of the incident electromagnetic field.OCIS codes: 190.4720, 160.4760. doi: 10.3788/COL201210.121901.Quantum dots (QDs) are quasi-zero-dimension systems, the carriers of which are confined in all the three spatial dimensions. These quantum systems, which were first studied by Esaki in 1970 [1] , are described as "artificial atoms" because of their δ-function-like density of states [2] . Unlike bulk crystals with band energies, QDs have discrete subbands because of their three-dimensional (3D) confinements. Intersubband transitions result in physical and optical properties and make QDs useful for infrared (IR) optoelectronic devices. The absorption coefficient (AC) and refractive index (RI) of the host material change because of the considerably large dipole matrix element and the low energy of intersubband transitions. In particular, the enhancement of nonlinear optical properties is important in QDs. Nonlinear properties depend on incident optical intensity; thus, at high incident intensities, the nonlinear properties should be considered.Researchers have recently investigated the electronic structure and the linear and nonlinear optical properties of different shapes of QDs, such as the box-shaped [1] , parabolic cylinder [3] , lens-shaped [4] , spherical [5] , and disc-like [6] QDs with finite, infinite, or Gaussian confining potential.Self-assembled InAs/GaAs QDs formed through Stranski-Krastanow growth can be pyramid-shaped [2] . These systems are important for laser applications [7] . Thus, researchers have approximated the pyramids by using cones to obtain the energy levels of conical quantum dots (CQDs) [8−10] . In this letter, a CQD with an infinite barrier potential is considered. The Schrödinger equation in the effective mass approximation is solved analytically to determine the electronic structure of CQDs. Subsequently, the linear, third-order nonlinear, and total AC and RI changes are investigated. Moreover, the dependencies of these optical properties on QD size and on the intensity and polarization of the incident electromagnetic field are studied.We consider that an electron confined in a CQD has an infinite barrier potential, i.e., V (r) = 0 inside and V (r) = ∞ outside the CQD. To solve this problem analytically, we consider several assumptions, i.e., we deem the potential outside of the QD to be infinite, although in reality, the wavefunctions penetrate into the host ma...

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“…The optical and electrical properties of the selfassembled QDs can be affected greatly by the wetting layer (WL) around the dots [2][3][4][5]. The WLs serve as channels for carriers to fall into dots and to redistribute between the dots, strongly influencing on the emission properties of the dots [2,3].…”

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confidence: 99%

Evolution of wetting layer in InAs/GaAs quantum dot system

Chen

Wang

2006

Nanoscale Res Lett

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For InAs/GaAs quantum dot system, the evolution of the wetting layer (WL) with the InAs deposition thickness has been studied by reflectance difference spectroscopy (RDS). Two transitions related to the heavy-and light-hole in the WL have been distinguished in RD spectra. Taking into account the strain and segregation effects, a model has been presented to deduce the InAs amount in the WL and the segregation coefficient of the indium atoms from the transition energies of heavy-and light-holes. The variation of the InAs amount in the WL and the segregation coefficient are found to rely closely on the growth modes. In addition, the huge dots also exhibits a strong effect on the evolution of the WL. The observed linear dependence of In segregation coefficient upon the InAs amount in the WL demonstrates that the segregation is enhanced by the strain in the WL.Keywords Quantum dots AE Wetting layer AE Reflectance difference spectroscopy AE Segregation PACS 78.67.Hc AE 68.65.Hb AE 73.21.Fg A strained epilayer with a thickness beyond a critical value will change from layer-by-layer growth (Frankvan der Merwe growth) to island growth (StranskiKrastanow growth) in order to relax strain energy. When covered by barrier materials, these self-assem-

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Bandstructures of conical quantum dots with wetting layers

Cited by 117 publications

References 22 publications

Influence of wetting-layer wave functions on phonon-mediated carrier capture into self-assembled quantum dots

Influence of wetting-layer wave functions on phonon-mediated carrier capture into self-assembled quantum dots

Exact investigation of the electronic structure and the linear and nonlinear optical properties of conical quantum dots

Evolution of wetting layer in InAs/GaAs quantum dot system

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