Strain in crystalline core-shell nanowires

Ferrand, D.; Cibert, J.

doi:10.1051/epjap/2014140156

Cited by 36 publications

(58 citation statements)

References 42 publications

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“…Many opportunities are then opened for a precise engineering of the envelope functions, not only through the natural band offsets, but also through a proper design of the built-in strain and the associated piezoelectric field and deformation potential. [5][6][7] In particular, it allows one to engineer the hole states in a semiconductor dot and tailor their orbital and spin states: a flat insertion induces a strain configuration (hence a light-hole heavy-hole splitting) quite similar to that of a dot made of the same materials but grown by the Stranski-Krastanov mechanism, while the configuration is reversed in a core-shell NW 7 or an elongated dot. This opens the opportunity to fully design the photonic properties of the nanostructure, and its magnetic properties if magnetic impurities are added.…”

Section: Introductionmentioning

confidence: 99%

“…12 Moreover, previous studies of heterostructured NWs based on tellurides (of Cd, Zn, Mg, Mn) suggest that they offer a great flexibility in their design in order to control the light-hole / heavyhole character of the confined ground state of holes. 7,[11][12][13][14][15] A low growth temperature (350 • C) was chosen to minimize the desorption of adatoms, particularly in view of the insertion of CdTe segments in the ZnTe NWs. We obtain tapered NWs with smooth sidewalls, and a well controlled insertion of CdTe and (Cd,Mn)Te.…”

Section: Introductionmentioning

confidence: 99%

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Diffusion-driven growth of nanowires by low-temperature molecular beam epitaxy

Rueda-Fonseca

Orrù

Bellet-Amalric

et al. 2016

Journal of Applied Physics

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With ZnTe as an example, we use two different methods to unravel the characteristics of the growth of nanowires by gold-catalyzed molecular beam epitaxy at low temperature. In the first approach, CdTe insertions have been used as markers, and the nanowires have been characterized by scanning transmission electron microscopy, including geometrical phase analysis, and energy dispersive electron spectrometry; the second approach uses scanning electron microscopy and the statistics of the relationship between the length of the tapered nanowires and their base diameter. Axial and radial growth are quantified using a diffusionlimited model adapted to the growth conditions; analytical expressions describe well the relationship between the NW length and the total molecular flux (taking into account the orientation of the effusion cells), and the catalyst-nanowire contact area. A long incubation time is observed. This analysis allows us to assess the evolution of the diffusion lengths on the substrate and along the nanowire sidewalls, as a function of temperature and deviation from stoichiometric flux.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Diffusion-driven growth of nanowires by low-temperature molecular beam epitaxy

Rueda-Fonseca

Orrù

Bellet-Amalric

et al. 2016

Journal of Applied Physics

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“…The AlGaAs shell can improve the carrier confinement in the core, suppressing the probability for non-radiative recombination on the GaAs NW core surface caused by their high SRV value. However, the theoretical studies of the strain state of such a one dimensional (1-D) system show that the strain at the GaAs/AlGaAs interface can be rather high 22 despite a small lattice mismatch between GaAs and AlAs. This is due to a shear stress which is important in this 1-D heterostructure configuration.…”

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confidence: 99%

Determination of the Optimal Shell Thickness for Self-Catalyzed GaAs/AlGaAs Core–Shell Nanowires on Silicon

et al. 2016

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We present a set of experimental results identifying various effects that govern the carrier dynamics of self-catalyzed GaAs/AlGaAs core-shell nanowires (NWs) grown by molecular beam epitaxy i.e. surface recombination velocity, surface charge traps, and structural defects.Time-resolved photoluminescence of NW ensemble and spatially-resolved cathodoluminescence of single NWs reveal that emission intensity, decay time and carrier diffusion length of the GaAs NW cores strongly depend on AlGaAs shell thickness but in a non-monotonic fashion. Although 7 nm-AlGaAs shell can efficiently suppress the surface recombination velocity of the GaAs NW cores, the effect of the band bending caused by the surface charges remains dominant if the shell thickness is less than 50 nm; that is, the carrier diffusion length is smaller in the NWs with a thinner shell caused by a stronger carrier scattering at the core/shell interface. If the AlGaAs shell thickness is larger than 50 nm, the luminescence efficiency of the GaAs NW cores starts to be deteriorated,

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“…For semiconductor NWs, a more complete calculation, 23 which is beyond the scope of this paper, shows that the previous expressions can be used for 111 oriented semiconductor NWs using the bulk modulus K = (c 11 + 2c 12 For the NWs studied in Ref. 7, with D c = 70 nm, D s =130 nm, and f = 1.04% corresponding to the lattice mismatch between a ZnTe core and a Zn 0.8 Mg 0.2 Te shell, 25 we obtain 2.31 eV for the heavy-hole exciton, in agreement with the observed PL line.…”

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confidence: 99%

Optical properties of single ZnTe nanowires grown at low temperature

Artioli

Rueda-Fonseca

Stepanov

et al. 2013

Applied Physics Letters

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Optically active gold-catalyzed ZnTe nanowires have been grown by molecular beam epitaxy, on a ZnTe(111) buffer layer, at low temperature (350 • C) under Te rich conditions, and at ultra-low density (from 1 to 5 nanowires per µm 2 ). The crystalline structure is zinc blende as identified by transmission electron microscopy. All nanowires are tapered and the majority of them are 111 oriented. Low temperature microphotoluminescence and cathodoluminescence experiments have been performed on single nanowires. We observe a narrow emission line with a blue-shift of 2 or 3 meV with respect to the exciton energy in bulk ZnTe. This shift is attributed to the strain induced by a 5 nm-thick oxide layer covering the nanowires, and this assumption is supported by a quantitative estimation of the strain in the nanowires. There is currently a wide-spread interest for semiconductor nanowires (NWs), driven by their potential to constitute suitable building blocks for future nanoelectronic and nanophotonic devices. 1 During the past decade, selenide and telluride II-VI NWs have been extensively investigated for various applications such as nano-pillar solar cells, 2 photodetectors 3 or single photon sources. 4 Among II-VI's, ZnTe based NWs are particularly promising as offering a large range of potentialities. They can be grown by molecular beam epitaxy (MBE) using gold particles as catalyst. They can be efficiently doped electrically. 5 They can also be doped with magnetic impurities, 6,7 while the large difference between the temperatures suitable for the growth of GaAs NWs and for the incorporation of Mn as substitutional impurities makes the growth of (Ga,Mn)As NWs challenging. 8 As (Zn,Mn)Te can be doped strongly p-type so that ferromagnetism appears and transport studies are feasible in 2D, 9 ZnTe-based NWs are attractive for a basic study of spintronics mechanisms in 1D. In addition, CdTe quantum dots can be incorporated and used as a single photon source 10 or as a very sensitive optical probe of the spin properties. 11 A good control and the optimization of the growth conditions are prerequisites to improve the electronic and optical properties of the NWs. We present the MBE growth and the structural analysis of ultra-low density ZnTe NWs and we show that their high crystalline quality allows us to observe micro-photoluminescence (µPL) and cathodoluminescence (CL) emission from single NWs.ZnTe NWs were grown by MBE, using gold particles as a catalyst. A thin layer of gold was deposited on a 500 nm-thick ZnTe(111) buffer layer previously grown on a GaAs(111)B substrate. Gold droplets were formed at 350 • C and the NWs were grown at the same temperature.

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Strain in crystalline core-shell nanowires

Cited by 36 publications

References 42 publications

Diffusion-driven growth of nanowires by low-temperature molecular beam epitaxy

Diffusion-driven growth of nanowires by low-temperature molecular beam epitaxy

Determination of the Optimal Shell Thickness for Self-Catalyzed GaAs/AlGaAs Core–Shell Nanowires on Silicon

Optical properties of single ZnTe nanowires grown at low temperature

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