Substrate-less diode, bipolar and feedthrough integrated circuit structures, and methods of fabricating substrate-less diode, bipolar and feedthrough integrated circuit structures, are described. For example, a substrate-less integrated circuit structure includes a semiconductor structure. A plurality of gate structures is over the semiconductor structure. A plurality of P-type epitaxial structures is over the semiconductor structure. A plurality of N-type epitaxial structures is over the semiconductor structure. One or more open locations is between corresponding ones of the plurality of gate structures. A backside contact is connected directly to one of the pluralities of P-type and N-type epitaxial structures.