A method for selective formation of a dual phase gallium nitride material on a (100) silicon substrate. The method includes forming a blanket layer of dielectric material on a surface of a (100) silicon substrate. The blanket layer of dielectric material is then patterned forming a plurality of patterned dielectric material structures on silicon substrate. An etch is employed that selectively removes exposed portions of the silicon substrate. The etch forms openings within the silicon substrate that expose a surface of the silicon substrate having a (111) crystal plane. A contiguous AlN buffer layer is then formed on exposed surfaces of each patterned dielectric material structure and on exposed surfaces of the silicon substrate. A dual phase gallium nitride material is then formed on a portion of the contiguous AlN buffer layer and surrounding each sidewall of each patterned dielectric material structure.