Abstract: An integrated circuit device consisting of an n-channel selectively doped heterojunction transistor (SDHT) and a p-channel SDHT, in the form of complementary MODFETs fabricated on the same wafer, is disclosed. A method for easily fabricating the complementary p- and n-MODFETs on the same wafer is also disclosed whereby a portion of a partially formed n-channel SDHT is implanted with p-type ions of sufficient dosage to transform the portion into a p-channel SDHT. The device is completed by etching an isolation gap between the n-channel and p-channel region, preferably no more than ten microns wide, and adding ohmic source and drain contacts as well as Schottky gate contacts. Many such MODFET pairs may be fabricated on a single wafer.