Method of fabricating an IC including electro-optical transmitters and receivers

An integrated circuit having active devices in electro-optical conversion material regions and single crystal silicon regions which are in a polycrystalline silicon support. The electro-optical conversion material regions are separated from the polycrystalline silicon by a containment layer. The method includes forming trenches in a wafer of electro-optical conversion material, covering the trenches with a containment layer and overfilling with polycrystalline silicon, removing material to expose polycrystalline silicon in the trenches and converting exposed portions of the polycrystalline silicon to single crystal silicon.