Interface engineered wetting-layer-free InAs quantum dots on GaAs(001)

Self-assembled quantum dots (QD) are nucleated by the strain induced at the wetting layer; which highly influences electrical, optical, and physical properties in PV applications. Isolating electronically QDs from their wetting layer (WL) for better performance and structural improvement is the aim of this work. Accordingly, we fabricate wetting layer free QDs by inserting an intermediate layer of GaAs(AlAs) in between the wetting layer and the dot layer by manipulating the strain accumulated in the WL. The structural and morphological characterizations were carried out using scanning transmission electron microscopy and atomic force microscopy. These analyses show that their novel strategy leads to significant improvement of dot structural characteristics as attested by the higher dot height/base aspect-ratio and by the presence of more evenly distributed and more symmetric dots. Finally optical properties were investigated by photoluminescence spectroscopy and show that the strategy results in enhanced luminescence efficiency and shaper emission line widths.