Electric-field effects on excitons in quantum dots

Using low-temperature microphotoluminescence spectroscopy we have investigated the effect of a lateral electric field on quantum dot excitons trapped by monolayer width fluctuations in a narrow quantum well. We observe a redshift of the ground state and several excited states, when a lateral field is applied. This Stark shift is reduced when the dot is populated with several excitons that screen the electric field. The lines broaden increasingly at high fields, which is attributed to field-induced lateral tunneling out of the dot.