A metal chalcogenide material layer of lower quality provides a transition between a metal chalcogenide material layer of higher quality and a gate insulator material that separates the metal chalcogenide material layers from a gate electrode of a metal-oxide semiconductor field effect transistor (MOSFET) structure. Gate insulator material may be more readily initiated and/or or precisely controlled to a particular thickness when formed on lower quality metal chalcogenide material. Accordingly, such a material stack may be integrated into a variety of transistor structures, including multi-gate, multi-channel nanowire or nanosheet transistor structures.