Magneto-photoluminescence study of quantum dots formed on tetrahedral-shaped recesses

Novel InGaAs quantum dot (QD) structures were fabricated in tetrahedral-shaped recesses (TSRs) formed on a GaAs (111)B substrate using low-pressure metalorganic chemical vapor deposition (MOCVD). The dots were formed in a self-forming manner at the bottom of TSRs due to the compositional nonuniformity of InGaAs grown inside the TSRs. To confirm directly zero-dimensional carrier confinement, magneto-photoluminescence (PL) measurements were performed for several InGaAs TSR-QDs under pulsed high magnetic fields in both Faraday and Voigt configurations. The diamagnetic shifts of QDs were clearly suppressed compared to the corresponding InGaAs quantum wells formed at the TSR sidewalk. The typical deduced Bohr radius from the hydrogen-like exciton model clearly proves a zero-dimensional carrier confinement into the TSR-QD. Moreover, the changes in the strength and anisotropy of the QDs' confinement potential obtained from the magneto-PL results were consistent with the intentional change in the design of the TSR-QDs. Through these studies, we clarified that it is possible to control the carrier confinement potential of TSR-QDs by independently changing the In-content and the thickness of InGaAs during MOCVD growth.