Internal field effects on electronic and optical properties of ZnO/BeZnO quantum well structures

The electronic and optical properties of ZnO/BeZnO quantum well (QW) structures were theoretically investigated by using the non-Markovian model with many-body effects. These results are compared with those of ZnO/MgZnO QW structures grown on ZnO substrates. For QW structures with a relatively small Be or Mg composition, spontaneous emission peaks of both QW structures are found to be comparable to each other. However, the emission peak intensity of the ZnO/BeZnO QW structure is greatly reduced with increasing Be composition because of the increase in the internal field due to the piezoelectric and spontaneous polarizations. On the other hand, the ZnO/MgZnO QW structure shows that its peak intensity is nearly independent of the Mg composition in the investigated range of Mg composition. This means that piezoelectric and spontaneous polarizations׳ effect is dominant in the ZnO/BeZnO system.