A fabrication process for a semiconductor device including a plurality of semiconductor layers, the plurality of semiconductor layers including at least a nitrogen-containing alloy semiconductor Al.sub.aGa.sub.bIn.sub.1-a-bN.sub.xP.sub.yAs.sub.zSb.sub.1-x-y-z (0.ltoreq.a.ltoreq.1, 0.ltoreq.b.ltoreq.1, 0