Methods are disclosed for fabricating a compound nitride semiconductor structure. An amorphous buffer layer that includes nitrogen and a group-III element is formed over a substrate disposed within a substrate processing chamber at a first temperature. The temperature within the chamber is increased to a second temperature at which the amorphous buffer layer coalesces into crystallites over the substrate. The substrate is exposed to a corrosive agent to destroy at least some of the crystallites. A crystalline nitride layer is formed over the substrate at a third temperature using the crystallites remaining after exposure to the corrosive agent as seed crystals. The third temperature is greater than the first temperature. The crystalline nitride layer also includes nitrogen and a group-III element.