Electronic and Optical Properties of Staggered ZnO/ZnO_1−xS _x-ZnO_1−yS _y/ZnO Quantum Wells for Bluish-Green Light-Emitting Diodes

The optical and electronic properties of staggered ZnO/ZnO_1−xS_x-ZnO_1−yS_y/ZnO (for x > y) bluish-green light-emitting diodes with quantum well (QW) structures are investigated using the multiband effective mass theory. The obtained results are compared with those of conventional ZnO_1−xS_x/ZnO QW structures, and the staggered QW structures are found to have a comparatively larger optical matrix, showing a substantial, yet gradual, reduction in the internal field effect. Thus, the staggered ZnO/ZnO_1−xS_x-ZnO_1−yS_y/ZnO QW structure design leads to a significantly higher spontaneous emission compared to that of conventional ZnO_1−xS_x/ZnO QW structures. This analysis indicates the potential of using a staggered QW structure for high-efficiency ZnO-based bluish-green LEDs.