Kiroubanand Sankaran

First-principles modeling of intrinsic and extrinsic defects in γ-Al2O3

The electronic properties of a set of intrinsic and extrinsic point defects in gamma-Al2O3 are investigated using quasiparticle calculations within the G(0)W(0) approximation. We find that the electronic signature of atomic vacancies lie deep in the band gap, close to the top of the valence band edge. The introduction of C, Si, and N impurities induces defective levels that are located close to the conduction band edge and near the middle of the band gap of the oxide. The comparison with electrical measurements reveals that the energy levels of some of these defects match with the electronic fingerprint of the defects reported in gamma-Al2O3 based nonvolatile memories

(Invited) First-Principles Investigation of High-k Dielectrics for Nonvolatile Memories

The microelectronic industry has devoted significant efforts to investigate alternative high dielectric constant oxides (high-κ) in order to sustain the reduction of the dimensions for the next technology nodes for high metaloxide semiconductors field effect transistors (MOSFET) performance [1-3]. The core of the problem consists of physically scaling the insulating dielectric without increasing the gate leakage current. While hafnium based dielectrics have been recognized as key materials for future application in MOSFET technological nodes, the requirements of Non-Volatile Memory (NVM) based devices have not been met yet.

(Invited) Probing the Intrinsic Limitations of the Contact Resistance of Metal/Semiconductor Interfaces through Atomistic Simulations

In this contribution, we report a fundamental study of the factors that set the contact resistivity between metals and highly doped semiconductors. We investigate the case of n-type doped Si contacted with amorphous TiSi combining first-principles calculations with Non-Equilibrium Green functions transport simulations. The intrinsic contact resistivity is found to saturate at ~2x10-10 Ω.cm2 with the doping concentration and sets an intrinsic limit to the ultimate contact resistance achievable for n-doped Si|amorphous-TiSi. This limit arises from the intrinsic properties of the semiconductor and of the metal such as their electron effective masses and Fermi energies. We illustrate that, in this regime, contacting metals with a heavy electron effective mass helps reducing the interface intrinsic contact resistivity.