Dislocation density reduction in GaN using porous SiN interlayers

The influence of a thin porous SiN_x interlayer on the growth of GaN by metalorganic chemical vapor deposition (MOCVD) has been studied. The interlayer is deposited on a GaN template by introducing silane in the presence of ammonia into the MOCVD chamber, and a GaN overlayer is deposited on the interlayer. The SiN_x interlayer produces inhomogeneous nucleation and lateral growth of the overlayer, causing bending of dislocations towards facet walls, and it also blocks some dislocations from entering the overlayer. The dislocation density for a GaN overlayer grown on a SiN_xinterlayer was reduced to 7 × 10⁸ cm^–2, which is an order of magnitude less than that for a control sample grown without an interlayer. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)