Excitonic Aharonov-Bohm effect in isotopically pure ⁷⁰Ge/Si self-assembled type-II quantum dots

We report on a magnetophotoluminescence study of isotopically pure ⁷⁰Ge/Si self-assembled type-II quantum dots. Oscillatory behaviors attributed to the Aharonov-Bohm effect are simultaneously observed for the emission energy and intensity of excitons subject to an increasing magnetic field. When the magnetic flux penetrates through the ringlike trajectory of an electron moving around each quantum dot, the ground state of an exciton experiences a change in its angular momentum. Our results provide the experimental evidence for the phase coherence of localized electron wave functions in group-IV Ge/Si self-assembled quantum structures. ©2010 The American Physical Society