The growth of InAs Quantum Dots (QDs) on InP(100) via droplet epitaxy in a Metal Organic Vapour Phase Epitaxy (MOVPE) reactor is studied. Formation of Indium droplets is investigated with varying substrate temperature, and spontaneous formation of nanoholes is observed for the first time under MOVPE conditions. Indium droplets are crystallized into QDs under Arsenic flow at different temperatures. For temperatures greater than 500ºC, a local etching takes place in the QD vicinity, showing an unexpected morphology which is found to be strongly dependent on the Received: (( ))Revised: (( )) Published online: (( ))

The structural and optical properties of InGaSb/GaP(001) type‐II quantum dots (QDs) grown by metalorganic vapor phase epitaxy (MOVPE) are studied. Growth strategies as growth interruption (GRI) after deposition of InGaSb and Sb‐flush prior to QD growth are used to tune the structural and optical properties of InGaSb QDs. The Sb‐flush affects the surface diffusion leading to more homogeneous QDs and to a reduction of defects. A ripening process during GRI occurs, where QD size is increased and QD‐luminescence remarkably improved. InGaSb QDs are embedded in GaP n + p‐diodes, employing an additional AlP barrier, and characterized electrically. A localization energy of 1.15 eV for holes in QDs is measured by using deep‐level transient spectroscopy (DLTS). The use of Sb in QD growth is found to decrease the associated QD capture cross‐section by one order of magnitude with respect to the one of In0.5Ga0.5As/GaP QDs. This leads to a hole storage time of almost 1 h at room temperature, which represents to date the record value for MOVPE‐grown QDs, making MOVPE of InGaSb/GaP related QDs a promising technology for QD‐based nano‐memories.

The optical response of (InGa)(AsSb)/GaAs quantum dots (QDs) grown on GaP (001) substrates is studied by means of excitation and temperature-dependent photoluminescence (PL), and it is related to their complex electronic structure. Such QDs exhibit concurrently direct and indirect transitions, which allows the swapping of Γ and L quantum confined states in energy, depending on details of their stoichiometry. Based on realistic data on QD structure and composition, derived from high-resolution transmission electron microscopy (HRTEM) measurements, simulations by means of k · p theory are performed. The theoretical prediction of both momentum direct and indirect type-I optical transitions are confirmed by the experiments presented here. Additional investigations by a combination of Raman and photoreflectance spectroscopy show modifications of the hydrostatic strain in the QD layer, depending on the sequential addition of QDs and capping layer. A variation of the excitation density across four orders of magnitude reveals a 50 meV energy blueshift of the QD emission. Our findings suggest that the assignment of the type of transition, based solely by the observation of a blueshift with increased pumping, is insufficient. We propose therefore a more consistent approach based on the analysis of the character of the blueshift evolution with optical pumping, which employs a numerical model based on a semi-self-consistent configuration interaction method.