Observation of the Stark effect in coupled quantum wells by electroluminescence and circularly polarized photoluminescence excitation spectroscopy

Successful observation is reported of the quantum-confined Stark effect in electroluminescence (EL) under a]] forward" electric-field condition, with a current injected into a p-i-n diode containing Al_0.3Ga _0.7As/GaAs symmetric coupled double quantum wells (CDQWs). The Stark shift observed in EL and (under a reverse bias) in photoluminescence (PL), in both of which the transitions involved are between the electron and heavy-hole lowest states, is found to be symmetrical with respect to the flatband bias, in agreement with calculations. The origin of the optical transitions between electron and light- or heavy-hole states in the CDQWs is also clearly identified by a combination of PL and circularly polarized photoluminescence excitation spectra.