Techniques are disclosed for using compositionally different contact materials for p-type and n-type source/drain regions on a common substrate. The different contact materials may be within a common source/drain contact trench, or in type-dedicated trenches. A given contact trench may span one or more fins and include one or more source/drain regions on which a corresponding contact structure is to be made. In an embodiment, an isolation structure between p-type and n-type fins is selective to the trench etch and therefore remains intact within the trench after the target source/drain regions have been exposed. In such cases, the isolation structure physically separates n-type source/drain regions from p-type source/drain regions. The contact structures on the different type source/drain regions may be shorted proximate the top of the isolation structure. Numerous material systems can be used for the channel and source/drain regions, including germanium, group III-V materials, and 2-D materials.