Photoluminescence and built-in electric field in ZnO∕Mg0.1Zn0.9O quantum wells

Photoluminescence study of ZnO∕Mg0.1Zn0.9O quantum wells with graded well width (Lw) was carried out at 4.2K. The emission evolution from quantum confinement regime to quantum-confined Stark regime was observed clearly. For large Lw, the emission splits into two peaks which are attributed to the emissions of ZnO band edge and separately localized carriers, respectively. The internal electric field in the well layer was estimated to be ∼0.3MV∕cm, being similar to previous reports. The results are useful in designing ZnO QW based optoelectronic devices.