Interfaces between a polar high-k perovskite and silicon
|Isabelle Devos 1, Pierre Boulenc 1,2|
1. Institut d'Electronique de Microélectronique et de Nanotechnologie (IEMN), BP 60069 - Cité scientifique-avenue Poincaré, Villeneuve d'Ascq 59652, France
In the search of high-κ materials deposited on silicon surfaces, we lace ourselves in the perspective of epitaxy which is chosen to try to avoid interface states. Oxides with the perovskite structure are known as good candidates as they can be considered as constructed on a superposition of layers which are compatible with the silicon surface. The main problem is to know the atomistic details about the interface as several possibilities generally exist to realize it, with several bonding.
We show here, taking the LaAlO3 perovskite as prototype, that this atomistic description is important on several points. It has first to insure that there are no gap states at the interface. To construct such an interface, one may use i) the "electron counting model" which we show that it has sometimes to be extended for polar oxides ii) ab initio electronic structure computations. We present several interfaces which have been constructed for LaAlO3 and their relaxed positions. Another important point to respect is the value of the conduction band offset. We demonstrate on computations in the density functional theory framework that the offset is greatly dependant on the interface (from -0.5eV to +3eV). From all these results, we deduce general rules about the high-κ materials interfaces with silicon.
Presentation: invited oral at E-MRS Fall Meeting 2005, Symposium F, by Isabelle Devos
See On-line Journal of E-MRS Fall Meeting 2005
Submitted: 2005-05-11 09:17 Revised: 2009-06-07 00:44