The present invention uses a treatment that involves an etching treatment that forms a pnictogen-rich region on the surface of a pnictide semiconductor film The region is very thin in many modes of practice, often being on the order of only 2 to 3 nm thick in many embodiments. Previous investigators have left the region in place without appreciating the fact of its presence and/or that its presence, if known, can compromise electronic performance of resultant devices. The present invention appreciates that the formation and removal of the region advantageously renders the pnictide film surface highly smooth with reduced electronic defects. The surface is well-prepared for further device fabrication.