Abstract

We calculated the crystal orientation dependence of piezoelectric fields in wurtzite strained Ga_0.9In_0.1N/GaN heterostructures. The highest longitudinal piezoelectric field of 0.7 MV/cm can be generated in (0001)-oriented biaxial-strained Ga_0.9In_0.1N layer coherently grown on GaN@. On the contrary, no longitudinal piezoelectric field is induced in strained layers grown along orientations at an off angle of 39^° or 90^° from (0001). The high symmetry planes with these angles are, for instance, (11\bar{2}4) and (10\bar{1}2) for 39^°, and (11\bar{2}0) and (10\bar{1}0) for 90^°. We also calculated the crystal orientation dependence of the transition probability in a 3-nm strained Ga_0.9In_0.1N/GaN quantum well, which indicated that the transition probability with these non-(0001) orientations becomes 2.3 times larger than that with the (0001) orientation. We conclude that high-performance strained nitride-based optical devices can be obtained by control of the crystal orientation.