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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 Al0.3Ga0.7As/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.