Quantum-confined Stark shift in electroreflectance of InAs/InxGa1-xAs self-assembled quantum dots

Electroreflectance was employed to study the electric-field effect on the i nterband transitions of InAs quantum dots embedded in an In0.16Ga0.84As mat rix. The electric field caused an asymmetric quantum-confined Stark shift, which revealed a nonzero built-in dipole moment in the quantum dots. We fou nd the ground-state and excited-state dipole moments to be in the same dire ction. The electron wave functions are distributed near the base of the qua ntum dot, with their centers located below the hole wave functions. We also observed a symmetric Stark shift in the wetting-layer transitions. This im plies that the wetting-layer potential is symmetric, despite its being capp ed with quantum dots. (C) 2001 American Institute of Physics.