Crystal orientation effects on electronic and optical properties of wurtzite ZnO/CdZnO quantum well lasers

• K.P method based valence band structure for c-, a- and m-planes were obtained for ZnO/CdZnO and GaN/InGaN of QW structures.
• Transition wavelength and momentum matrix elements were presented as a function of crystal orientation angles.
• The optical gain was studied taking into account many body effects and spontaneous-piezoelectric built-in field.
• The optical gain showed larger values in non-polar structures.

The study of electronic and optical properties of ZnO/CdZnO quantum well (QW) structures, considering the crystal orientation dependence and Gaussian line shape function for optical gain are explored including many body effects and spontaneous-piezoelectric built-in field. Results are confronted with those for GaN-based QW structures. The effect of internal field in the c-plane oriented ZnO/CdZnO QW structure is relatively small compared to that of GaN/InGaN QW structure and thus, a larger optical gain is shown while it disappears in the a- and m-planes for both QW structures where the optical gain as a result is match larger. Energy dispersion, transition strength and the average hole effective masses are anisotropic in non-polar structures. The bandgap transition wavelength of the QW structure with a-plane orientation is smaller than that of m-plane orientation by 2 nm in ZnO/CdZnO QW while it is 10 nm in the case of GaN/InGaN QW structure.