We use droplet epitaxy to create tensile-strained GaP quantum dots in a GaAs matrix. A strong biaxial tensile strain leads to the formation of a type-II band lineup with a transition energy lower than the bulk GaAs band gap. The luminescence transients exhibit highly non-exponential decay behavior with an average time constant of 11 ± 2 μs, which is more than three orders of magnitude longer than the lifetime of standard type-I quantum dots. The prolonged luminescence decay time for the GaP/GaAs dots confirms the formation of the type-II band alignment associated with the tensile strain.

We report on the study on effect of Ga pre-deposition rate on GaAs nanowires grown by self-assisted vapor-liquid-solid (VLS) method. Ga droplets were initially deposited on the surface of Si(111) substrates covered with thin layer of SiO2. The nanowires were grown by molecular beam epitaxy (MBE). Dependency of structural of nanowires on Ga pre-deposition rate is investigated by Scanning Electron Microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX), and X-ray Diffraction Analysis (XRD). The experimental results show that the different in Ga pre-deposition rate significantly affect the surface morphology of samples. Growth rate and the density of nanowires strongly depends on the Ga pre-deposition rate.

We have demonstrated the fabrication of lateral InAs quantum dot molecules (QDMs) on InGaAs square-like nanohole templates by 2-step growth technique using solid-source molecular beam epitaxy (MBE). In this work, the first step of fabrication process is droplet epitaxial (DE) growth to form the InGaAs square-like nanoholes at low temperature. Then, the substrate was ramped up to high temperature with a constant rate. At this stage, the square-like nanoholes transform into nanomounds (NMs). Finally, the lateral InAs QDMs were grown on the InGaAs NMs via Stranski-Krastanow (SK) technique. The result of this work, the QD formation mostly appears at the corner of the nanomound or deformed square-like nanohole since the corner has high compressive-strain field.

The GaAs nanowires are grown on Si (111) substrates by Ga-assisted molecular beam epitaxy growth technique. The effect of SiO2 thickness on the structural properties of GaAs nanowires is investigated by Scanning Electron Microscope (SEM). The nucleation of GaAs nanowires related to the presence of a SiO2 layer previously coated on Si substrate. The results show that the density, length, and diameter of GaAs nanowires strongly depend on the oxidation time (or SiO2 thickness).

We report on the molecular beam epitaxial growth of self-assembled GaSb quantum dots (QDs) on (001) GaAs substrates with an insertion layer. The insertion layer, which is a 4-monolayers (MLs) InxGa1−xAs (x=0.00, 0.07, 0.15, 0.20 and 0.25), is grown prior to the QD growth. With this InGaAs insertion layer, the obtained QD density decreases substantially, while the QD height and diameter increase as compared with typical GaSb QDs grown on conventional (001) GaAs surface under the same growth condition. The GaSb QDs on GaAs have the dome shape with elliptical base and the elongation direction of the base is along the [110] direction. When the InGaAs insertion layer is introduced, the distinct elongation disappears and the QD sidewall shows facet-related surfaces with (001) plateau on top.

We present the fabrication of GaSb quantum rings (QRs) on the GaAs (001) substrates by droplet epitaxy technique using solid-source molecular beam epitaxy (MBE). In droplet epitaxy process, Ga was deposited on GaAs surface to form liquid Ga droplets and then exposed to Sb flux for crystallization. The evolution of Ga droplets into GaSb QRs is discussed and tracked by means of reflection high energy electron diffraction (RHEED) and atomic force microscopy (AFM).

We present the fabrication of GaP ring-like nanostructures on GaAs ( 100) substrates with inserted In0.15Ga0.85As compensation layers. The samples are grown by droplet epitaxy using solid-source molecular beam epitaxy. The dependency of nanostructural and optical properties of GaP nanostructures on In0.15Ga0.85As layer thickness is investigated by ex-situ atomic force microscope (AFM) and photoluminescence (PL). It is found that the characteristics of GaP ring-like structures on GaAs strongly depend on the In0.15Ga0.85As layer thickness.