InAs nanostructures were grown on ${\mathrm{In}}_{\text{0.52}}{\mathrm{Al}}_{\text{0.48}}\mathrm{As}$ alloy lattice matched on InP(001) substrates by molecular beam epitaxy using specific growth parameters in order to improve island self-organization. We show how the change in InAs surface reconstruction via growth temperature from $\text{(2×4)}$ to $\text{(2×1)}$ and/or the use of InAlAs initial buffer surface treatments improve the island shape homogeneity (either as quantum wires or as quantum dots). Differences in island shape and in carrier confinement are shown by atomic force microscopy and by photoluminescence measurements, respectively. We point out that such shape amendments induce drastic improvements to island size distribution and discernible changes in photoluminescence properties, in particular concerning polarization.

The introduction of hydrogen chloride during the in situ doping of silicon nanowires (SiNWs) grown using the vapor-liquid-solid (VLS) mechanism was investigated. Compared with non-chlorinated atmospheres, the use of HCl with dopant gases considerably improves the surface morphology of the SiNWs, leading to extremely smooth surfaces and a greatly reduced tapering. Variations in the wire diameter are massively reduced for boron doping, and cannot be measured at 600 °C for phosphorous over several tens of micrometers. This remarkable feature is accompanied by a frozen gold migration from the catalyst, with no noticeable levels of gold clusters observed using scanning electron microscopy. A detailed study of the apparent resistivity of the NWs reveals that the dopant incorporation is effective for both types of doping. A graph linking the apparent resistivity to the dopant to silane dilution ratio is built for both types of doping and discussed in the frame of the previous results.

We show how the height dispersion of self-organized InAs/InP(001) quantum islands emitting at 1.55 μm was reduced by optimizing the epitaxial growth parameters. Low height dispersion was obtained when the InAs deposit thickness was much greater than the critical thickness for two-dimensional/three-dimensional growth mode transition, and when adatom surface diffusion was favored by increasing the growth temperature or reducing the arsenic pressure during the InAs growth. When these growth conditions are not respected, the multicomponent photoluminescence spectrum obtained is explained through the common interpretation of island height varying with monolayer fluctuation. In optimized growth conditions, the multicomponent spectrum obtained is interpreted as emission from fundamental and excited levels of InAs islands with low height dispersion. Transmission electron microscopy (TEM) imaging shows that these InAs islands are stick-like, 50–100 nm in length and 22±1.2 nm in width. Cross-sectional TEM reveals flat islands, shaped like truncated pyramids, with a very homogeneous height measured at 2.4 nm. A fundamental level linewidth of 22 meV at 8 K is associated to this very narrow height distribution. Such low photoluminescence linewidth values are believed to be mainly due to the propensity of the InAs/InP(001) system to produce flat InAs islands with discrete height fluctuation.

We grew Si nanowires by chemical vapor deposition, via the vapor liquid solid growth, using silane as gaseous precursor and gold as catalyst. The results show that the nanowire length depends on their diameter. For nanowires with diameter under 100 nm, the length increases when diameter increases, because of an increase in the growth velocity. For the thicker diameter $\left(d>100\text{nm}\right)$ , length decreases when diameter increases, due to an apparent incubation time which is all the higher as the diameter is high. We propose a semiempirical model combining Gibbs–Thomson effect and incubation time, which shows good agreement with the experimental data.

Carrier confinement in InAs quantum dashes (QDas) grown on InP(001) is investigated both experimentally and theoretically. The aim of these studies is to reconstruct the electronic structure of the QDas. QDas with low size dispersion are achieved by improving growth conditions. Optical transitions between ground and excited states are studied by continuous-wave-photoluminescence and photoluminescence-excitation experiments at low temperature. We also report on infrared spectroscopy of conduction-band intersubband transitions. A simplified theoretical model is developed, yielding results consistent with the experimental data. Combining experimental and theoretical results, we propose an interpretation of the optical transitions occurring in these QDas, and we give a first theoretical absorption spectrum of these structures.