In this paper we report on our work on the monolithic integration of various III-V compounds on Si using template-assisted selective epitaxy (TASE) and its application for electronic devices. Nanowires, crossbar nanostructures, and micron-sized sheets are epitaxially grown on Si via metal-organic chemical vapor deposition and form the basis for III-V MOSFETs and Tunnel FETs. Epitaxy conditions specific to TASE are discussed and material quality assessed. Here, we focus on InAs and GaSb as a potential all-III-V alternative to complementary group IV technology. Scaled n-FETs as well as both n- and p-channel TFETs are fabricated on Si and illustrate the potential of TASE.