Gate oxide quality for complex MOSFET devices

In various aspects, methods of forming a semiconductor device and semiconductor devices are provided. In some illustrative embodiments herein, a silicon/germanium layer is provided on a semiconductor substrate. On the silicon/germanium layer, at least one insulating material layer is formed. After having performed a thermal annealing process, the at least one insulating material layer is removed in subsequent process sequences such that the silicon/germanium layer is at least partially exposed. In further processing sequences which are to be subsequently applied, a gate electrode is formed on the exposed silicon/germanium layer.