Hole localization energy of 1.18 eV in GaSb quantum dots embedded in GaP

Self-organized GaSb quantum dots are embedded in GaP by molecular beam epitaxy and n+p-diodes are fabricated. The structure of the sample is investigated using transmission electron microscopy with atomic resolution. The presence of quantum dots on top of a wetting layer and interdiffusion processes between Sb and P are observed. The localization energy, capture cross-section, and storage time of holes in the ground state of the quantum dots are determined via deep-level transient spectroscopy. Their localization energy of 1.18(±0.01)eV is found to agree with the theoretical prediction of 1.4 eV once the observed interdiffusion is taken into account. A storage time of holes of 3.9(±0.3) days at room temperature is calculated, marking an improvement of 3 orders of magnitude from previous record figures. GaSb/GaP quantum dots are, thus, promising candidates for future non-volatile DRAMs or fast Flash. Schematic representation of the quantum dots (left) and of the valence band in their vicinity (right). The localization energy is marked on the scheme. The localization of the quantum dots prevents thermal emission of holes, generating a storage time at room temperature of 3.9 days.