Figure 1.

RSMs around the (12–33) GaN reflection of samples S1 (a) and S2 (b). Inset of (a) illustrates the influence of mosaicity parameters (lateral correlation length (D_lateral) and tilt () of blocks) on RLPs. Inset of (b) illustrates the scheme of fully strained and totally relaxed layer (L) on substrate (S) in reciprocal space. The solid and dashed lines between RS points are guides to the eye which indicate the in-plane strain state of the SLs. Q_z and Q_x are the reciprocal space coordinates, which are perpendicular and parallel to the surface, respectively.