The present disclosure provides a semiconductor device comprising a substrate, an undoped HfO2 layer formed over the substrate and a TiN layer formed on the HfO2 layer. Herein, the undoped HfO2 layer is at least partially ferroelectric. In illustrative methods for forming a semiconductor device, an undoped amorphous HfO2 layer is formed over a semiconductor substrate and a TiN layer is formed on the undoped amorphous HfO2 layer. A thermal annealing process is performed for at least partially inducing a ferroelectric phase in the undoped amorphous HfO2 layer.