A fabrication method produces a mechanically patterned layer of group III-nitride.
The method includes providing a crystalline substrate and forming a first layer
of a first group III-nitride on a planar surface of the substrate. The first layer
has a single polarity and also has a pattern of holes or trenches that expose a
portion of the substrate. The method includes then, epitaxially growing a second
layer of a second group III-nitride over the first layer and the exposed portion
of substrate. The first and second group III-nitrides have different alloy compositions.
The method also includes subjecting the second layer to an aqueous solution of
base to mechanically pattern the second layer.