Embodiments relate to growing an epitaxy gallium-nitride (GaN) layer on a porous silicon (Si) substrate. The porous Si substrate has a larger surface area compared to non-porous Si substrate to distribute and accommodate stress caused by materials deposited on the substrate. An interface adjustment layer (e.g., transition metal silicide layer) is formed on the porous silicon substrate to promote growth of a buffer layer. A buffer layer formed for GaN layer may then be formed on the silicon substrate. A seed-layer for epitaxial growth of GaN layer is then formed on the buffer layer.