Theoretical study of O- and Zn-face polarity effect on the optical properties of the conventional and staggered ZnO/Zn1-xCdxO/ZnO quantum wells

In this work we present a comparative study of Zn-face and O-face polarity Zn1xCdxO-based conventional and staggered quantum-well (QW) structures. The calculation of optical properties of QWs was performed by means of self-consistent Schrodinger-Poisson solver with consideration of polarization-induced effects. The conventional Zn-face and O-face QWs possess similar values of transition energy and an overlap of electron and hole wave functions. A change of the polarity from Zn-face to O-face for the conventional QWs influences only a shape of the conduction and valence band edge profile. It is revealed that the utilization of the staggered QWs leads to an improvement of the confinement characteristics. In addition, the O-face staggered QW structure has larger values of transition energy and overlap integral compared to the Zn-face staggered QW structure. O-terminated staggered QW structure is less dependent on a well thickness and has lower sensitivity to Cd content in embedded Zn1-xCdxO layer. Controlling the material polarity and designing the staggered QWs provide cost-effective approaches to engineer the QW band structures for enhancing the QW performance, which has great potential to achieve Zn1-xCdxO-based light emission diodes with improved radiative efficiency emitting applicable for solid state lighting.