Observation of the quantum confined stark effect in ZnSe/ZnCdSe single quantum well systems

We report the observation of the quantum-confined Stark effect (QCSE) in ZnSe/ZnCdSe single quantum wells grown by molecular beam epitaxy, using photoluminescence. In our experiments the electric field was applied via a reverse-biased Schottky barrier contact. To our knowledge, this is the first observation of the QCSE in any wide gap II-VI semiconductor heterostructure. Significant red shifts, typically 10-15 meV, are detected before quenching. An associated reduction in the transition intensity, consistent with the QCSE, is clearly observed. The dependence of these results will be discussed as a function of quantum well depth and thickness. Complete quenching of the luminescence is observed with applied voltages as low as 5 V. In addition, at lowest voltages, we also detect small blue shifts (up to 4 meV), which we attribute to the interaction between the externally applied electric field and the built-in field of the structure.