[en] We present a theoretical study of the dopant spatial distribution in III–V nanowires grown by molecular beam epitaxy. The evolution of the dopant concentration is obtained by solving the non-stationary diffusion equation. Within the model, it is shown why and how the dopant inhomogeneity appears, as observed experimentally in the case of Be doping of GaAs nanowires and in other material systems.

[en] This theoretical work deals with polytypism in nanowires by utilizing nucleation theory and by modifying standard expression for nucleation rate. Polycentric and monocentric nucleation cases are also considered. Results show good agreement with experimental data. (paper)

[en] By applying the Redlich-Kister polynomial model, we calculate chemical potentials of quaternary liquid alloys during the gold-catalyzed vapor-liquid-solid growth of ternary In_xGa_1-xAs nanowires. We then use these chemical potentials in the Zeldovich nucleation rate to obtain the nanowire axial growth rates versus the deposition conditions and indium compositions. (paper)

[en] We report on a dopant incorporation mechanism in core-shell nanowires fabricated via the vapor-liquid-solid growth method. In particular, a solution to the diffusion equation for the dopant profile in the core in the general case of spatial anisotropy is obtained. This allows us to describe the evolution of the dopant concentration during the nanowire growth. Within the model, we show that the dopant inhomogeneity arises from the NW core morphology. We also describe qualitatively the entire diffusion process. It is shown how to achieve the homogeneous dopant distribution. (paper)

[en] The nucleation of islands during the first order phase transition in a materially open system is studied. Expressions for the island size and density are obtained as functions of the temperature, material flux and the total concentration of material introduced into the system. It is shown that at a certain critical concentration the transition from the thermodynamically to the kinetically controlled regime of nucleation is observed. In the subcritical range the density of islands increases with temperature and the amount of material and is flux independent. In the overcritical range the density decreases with the temperature, increases with the flux and does not depend on the total concentration. The characteristic size of the islands decreases simultaneously with the increase of their density

[en] In this work we study features of vapor-solid-liquid mechanism of nanowire growth. We consider variation of droplet volume during the growth caused by droplet depletion and refilling. Here we take into account the changes in material transport due to volume variation, which was neglected previously. We also discuss the impact of this effect on nanowire length distributions. (paper)

[en] A new numerical approach for the determination of the GaN nanowire surface density on an AlN/Si substrate as a function of the growth time and gallium flux is presented. Within this approach, the GaN island solid-like coalescence and island-nanowire transition are modeled by the Monte-Carlo method. We show the importance of taking into consideration the island coalescence for explaining that the maximum of GaN island surface density is several times larger than the maximum of GaN nanowire surface density. Also, we find that the nanowire surface density decreases with an increase of the gallium flux. (paper)

[en] A kinetic model for contact angle stability is introduced for the non-stationary case with time-dependent fluxes in a molecular-beam epitaxy chamber. We present numerical simulations for different regimes of the nanowire growth process. (paper)

[en] Herein, we present an analytic length distribution of vapor–liquid–solid nanowires growing without the nucleation delays of the very first monolayer, by the direct impingement of material from vapor, and in the absence of desorption. We show that nucleation antibunching narrows the Poissonian length distribution to a time-independent asymptotic shape. The obtained distribution depends on the sole control parameter $\mathrm{\epsilon <!--\; ??\; -->}$ describing the effect of antibunching, and has a variance of $1/\left(2\mathrm{\epsilon <!--\; ??\; -->}\right)$ rather than spreading infinitely with time. A good agreement is found between the analytic shapes obtained within the continuum growth theory and Green’s function of the discrete rate equations describing the length statistics of nanowires. Overall, this narrowing effect can be used to improve the size homogeneity of III–V and other semiconductor nanowires grown under the appropriate conditions. (paper)

[en] A theoretical model for calculating the distribution of quantum dots in size in the case of growth according to the Stranski-Krastanow mechanism in the lattice-mismatched heteroepitaxial systems is suggested. The model is based on the general theory of the islands' nucleation at the first-order phase transition, in which situation the role of the metastable phase is played by the overstressed wetting layer, while the elastically stressed three-dimensional islands act as nuclei of the new phase. The suggested model clarifies and generalizes a number of the results reported previously. The theory can be used at the kinetic stage of formation of quantum dots, in which case their ensemble is noninteracting. An example of calculation of the kinetics for formation of hut-shaped clusters in the heteroepitaxial Ge/Si(100) system is given