Embodiments described herein may be related to apparatuses, processes, and techniques related to a transistor structure that includes a buried power rail (BPR) located within the transistor structure at a level below a height of one or more of the fins of the transistor structure. The BPR may be located proximate to a bottom substrate of the transistor structure. In embodiments, the transistor structure includes a protective layer, which can include one or more dielectric layers, above the BPR to protect the BPR during stages of transistor structure manufacture. In embodiments, portions of the protective layer may also be used to constrain epitaxial growth during stages of manufacturing of the transistor structure. Other embodiments may be described and/or claimed.