Improvement of (1122) Semipolar GaN Crystal Quality with TiN Interlayer by Metal Organic Vapor Phase Epitaxy

The effect of a TiN interlayer on the crystalline quality of (1122) semipolar GaN grown on m-plane sapphire was studied by high-resolution X-ray diffraction (HRXRD). Before GaN growth, a TiN interlayer was formed by nitrided the Ti metal on the GaN seed layer. Symmetric and skew-symmetric HRXRD measurements demonstrate that both threading dislocation and basal plane stacking fault densities are reduced. Raman results also show an increased crystalline quality and a decreased threading dislocation density. (1122) semipolar GaN with an optimal Ti thickness of 2 nm has been obtained under the existing growth conditions.