Papers by Keyword: Droplet Epitaxy

Abstract: Semiconductor nanostructures are referred to semiconductor heterostructures confined in one, two, or all three dimensions, which are known as quantum wells, quantum wires, and quantum dots (QDs), respectively. QDs are semiconductor nanocrystals with significant potential for high-performance photonic and electronic devices based on III–V semiconductor alloys. To fabricate these structures, several methods have been developed, including chemical synthesis of colloidal QDs, Stranski–Krastanov (S–K) growth technology, and droplet epitaxy (DE). DE is an epitaxial technique primarily employed for fabrication of nanostructures based on III–V semiconductors for quantum information technology applications. This work presents a DE technology of growth of InGaP nanocrystals on GaP surface. The technology includes the electrochemical deposition of group III metals on the III–V semiconductor surface, followed by annealing in inert gas atmosphere. The photoelectric and photonic properties of the resulting nanomaterials are analyzed. Based on the experimental results and literature data, the growth mechanism of InGaP nanocrystals on the GaP surface is described, and a phenomenological model for the formation of InGaP/GaP nanostructures is proposed.

Abstract: We study the GaSb/GaAs nanostructures (NSs) grown by droplet epitaxy technique with various Ga amounts. Ga amount deposited on the GaAs (001) substrate was varied between 3-5 ML to form the different size and density of liquid Ga droplets. The Sb flux was subsequently irradiated to crystallize the droplets. Morphology of GaSb NSs was investigated by atomic force microscopy (AFM). Quantum rings were obtained after crystallizing 3-ML Ga droplets, whereas some kind of quantum dots were formed after crystallizing 4-and 5-ML Ga droplets. The formation mechanisms leading to the different structure are discussed. The photoluminescence (PL) measurement was performed to examine the optical properties of GaSb/GaAs NSs.

Abstract: We report on the fabrication of self-assembled InP ring-shape nanostructures on In0.49Ga0.51P by droplet molecular-beam epitaxy. The dependency of InP ring-shape nanostructural properties on substrate temperature and indium deposition rate is investigated by ex situ atomic force microscope (AFM). The nano-craters are formed when indium deposition at 120°C while the ring shape quantum-dot molecules are formed when indium deposition at 150°C or higher. The size, density and pattern of InP ring-shape nanostructures strongly depend on substrate temperature and indium deposition rate during indium deposition.

Abstract: Fabrication of semiconductor nanostructures such as quantum dots (QDs), quantum rings (QRs) has been considered as the important step for realization of solid state quantum information devices, including QDs single photon emission source, QRs single electron memory unit, etc. To fabricate GaAs quantum rings, we use Molecular Beam Epitaxy (MBE) droplet technique in this report. In this droplet technique, Gallium (Ga) molecular beams are supplied initially without Arsenic (As) ambience, forming droplet-like nano-clusters of Ga atoms on the substrate, then the Arsenic beams are supplied to crystallize the Ga droplets into GaAs crystals. Because the morphologies and dimensions of the GaAs crystal are governed by the interplay between the surface migration of Ga and As adatoms and their crystallization, the shape of the GaAs crystals can be modified into rings, and the size and density can be controlled by varying the growth temperatures and As/Ga flux beam equivalent pressures(BEPs). It has been shown by Atomic force microscope (AFM) measurements that GaAs single rings, concentric double rings and coupled double rings are grown successfully at typical growth temperatures of 200°C to 300°C under As flux (BEP) of about 1.0×10-6 Torr. The diameter of GaAs rings is about 30-50 nm and thickness several nm.