Stress relaxation in semipolar and nonpolar III-nitride heterostructures by formation of misfit dislocations of various origin

Abstract

We present an analytical model describing misfit stresses relaxation in semipolar III-nitride heterostructures caused by misfit dislocations (MDs) originating from basal or prismatic slip and by sessile MDs. We analyze the critical thickness hc for the formation of MDs depending on crystal lattice mismatch and orientation of the semipolar growth plane. We explore transversely isotropic elasticity solutions to describe the relaxation processes in III-nitride semipolar heterostructures and compare the results for hc with those calculated within the isotropic elasticity approach. We find that the value of angle ϑ between the polar с-axis, and the direction of heterostructure growth has an impact on the realization of the stress relaxation mechanism by the generation of MDs originating either from basal or prismatic slip. A comparison of theoretical calculations with experimental data on the observation of MDs in the III-nitride heterostructures is provided.

Stress–strain state in α-Ga2O3 epitaxial films on α-Al2O3 substrates

“…rhombohedral and hexagonal, descriptions, it is rather difficult to predict the influence of the constant C 14 on the relaxation process due to misfit dislocations (MDs) formation at the heterostructure interface, because of the fact that different components of stress tensor can be relaxed depending on the operation of active dislocation slip systems, for the case of semipolar III-nitrides, see Ref. 32. Nevertheless, one can expect that in the case of formation of MDs from basal slip, the differences between the rhombohedral and hexagonal descriptions will be insignificant, but for the formation of MDs from prismatic slip these differences can be more pronounced.…”

Influence of an InGaN superlattice pre-layer on the performance of semi-polar (11–22) green LEDs grown on silicon

“…The critical thicknesses for stress relaxation via the formation of misfit dislocations depends on growth orientation. Detailed studies confirm that the critical thickness of InGaN grown on (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) GaN is much thinner than for growth on c-plane GaN or (20-21) semi-polar GaN [26][27][28][29][30] . Therefore, although the InN content in the InGaN of the SLS pre-layer is as low as 3%, misfit dislocations are still generated.…”

Misfit Stress Relaxation in α-Ga2O3/α-Al2O3 Heterostructures via Formation of Misfit Dislocations

“…In the model proposed below, we implement the approach developed for describing misfit stress relaxation in wurtzite-type heterostructures [20,21] using the hexagonal geometry of a unit cell of the contacting α-Ga 2 O 3 and α-Al 2 O 3 phases but introducing additional constant C 14 into corresponding equations. Let us consider the process of misfit stress relaxation in α-Ga 2 O 3 /α-Al 2 O 3 heterostructures with different orientations of the film growth due to formation of MDs in the geometry and with designations presented in Fig.…”