Dresden 2006 – scientific programme

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HL: Halbleiterphysik

HL 23: Interfaces/surfaces

HL 23.8: Talk

Tuesday, March 28, 2006, 19:00–19:15, BEY 154

Electronic structure at Si-Insulator interfaces — •Rebecca Janisch, Alberto Martinez-Limia, and Christian V. Radehaus — Institute for Electrical and Information Engineering, Technical University Chemnitz, 09107 Chemnitz, Germany

Several materials systems are currently under consideration as potential alternatives to SiO$_2$ as the gate dielectric material for complementary metal-oxide-semiconductor (CMOS) technology. One of the main challenges for the alternative high-k dielectric are the advantageous structural features of the Si-SiO$_2$ interface. Pseudobinary alloys of SiO$_2$ and the oxides of the group-IV transition metals Ti, Zr, and Hf are currently considered to be the most promising candidates that combine the outstanding structural features of the former with excellent dielectric properties of the latter.

To study the electronic properties of Si-high-k interfaces, we performed ab initio calculations employing the ABINIT and the CPMD electronic structure code. In a first step we constructed a model Si-SiO$_2$ interface. After structural optimization we calculated site-projected density of states (DOS) for representative atoms in the supercell. From these we were able to derive information about band-offsets and the density of interface states. Starting with the relaxed structure of the Si-SiO$_2$ interface we then substituted selected Si atoms in the SiO$_2$ slab with Ti or Zr respectively. We currently investigate the preferred position of the substituting atom, its influence on the bulk and interface structure, as well as the resulting changes in the electronic structure at the interface. We will discuss the results of this ongoing work in this presentation.