In the present talk we discuss the development of the epitaxial technique Template-Assisted Selective Epitaxy (TASE)and its application for the monolithic integration of scaled III-V active photonic devices on silicon. A unique advantage of TASE for silicon photonics applications is that it enables a truly local integration of III-V material at precisely defined positions, it is therefore particularly suited for densely Integrated nanophotonic devices. Here we will discuss our work on InP-based microdisk lasers fabricated by either direct TASE growth or via the use of micro-substrates. Optical mode simulations using Lumerical are used to explore the design space. Notably, we are exploring the use of metal-clad cavities for further light confinement. The metal-clad cavities enable scaling of the laser diameter beyond what is achievable with a pure photonic cavity. Thermal simulations are used to explore the impact of the metal-cladding as a heat sink as opposed to plasmonic operation. We also evaluate the potential for electrical actuation and will show first results on monolithic photodetectors, using Sentaurus simulations to improve our understanding of device performance.