Methods of direct growth of high quality group III-V and group III-N based materials and semiconductor device structures in the form of nanowires, planar thin film, and nanowires-based devices on metal substrates are presented. The present compound semiconductor all-metal scheme greatly simplifies the fabrication process of high power light emitters overcoming limited thermal and electrical conductivity of nanowires grown on silicon substrates and metal thin film in prior art. In an embodiment the methods include: (i) providing a metal substrate; (ii) forming a transition metal dichalcogenide (TMDC) layer on a surface of the metal substrate; and (iii) growing a semiconductor epilayer on the transition metal dichalcogenide layer using a semiconductor epitaxy growth system. In an embodiment, the semiconductor device structures can be compound semiconductors in contact with a layer of metal dichalcogenide, wherein the layer of metal dichalcogenide is in contact with a metal substrate.