The calculation of semipolar orientations for wurtzitic semiconductor heterostructures: application to nitrides and oxides

We investigate how the template crystal orientation indices (hk. l) can influence the intensity of density of elastic energy and polarization fields in wurtzite nitrides and oxides semiconductor strained layer heterostructures. We propose analytical relations between the angle Theta, defined as the direction of the sixfold axis of unstrained material and the direction normal to the growth plane, and (i) the value of the total polarization and (ii) the density of elastic energy stored in the strained layer. We find that quasi-cancellation of quantum confined stark effect (QCSE) can be generally obtained by carefully selecting the (hk. l) set. This situation does not lead to minimal strain density of elastic energy, but the increase of this parameter may be moderate compared to the minimum value. In the case of materials submitted to biaxial tension, we observe that the total density of elastic energy stored shows no minimum except when Theta = 0.