TiO2 has a dielectric constant of over 80 while commonly used high-k materials such as HfO2 have much lower values of around 20. Based on this property alone it would suggest that TiO2 is better than HfO2. Obviously, there is something I'm missing as TiO2 would be the dielectric of choice, I am wondering what is the reason(s) for HfO2 being superior.
Is it not possible to deposit high quality TiO2 via ALD (or other processes) or are there other reasons such as the films displaying unsuitable properties (e.g. resistive switching) or not having a high enough energy barrier to prevent charge injection?