Screening and polaronic effects induced by a metallic gate and a surrounding oxide on donor and acceptor impurities in silicon nanowires

Mamadou Diarra (1) , Christophe Delerue (1, 2) , Yann-Michel Niquet (3) , Guy Allan (1)

1 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520
2 PHYSIQUE - IEMN - Physique - IEMN
3 SP2M - UMR 9002 - Service de Physique des Matériaux et Microstructures

We present self-consistent tight binding calculations of the electronic structure of donor and acceptor impurities in silicon nanowires surrounded by a gate oxide SiO2 or HfO2 and a metallic gate. These environments efficiently screen the potential of the impurities so that their ionization energy strongly decreases with respect to the case of freestanding nanowires. It is also shown that the carriers trapped by the impurities form a polaron due to the response of the ions in the surrounding oxide layer. We predict that the polaron shift represents a large part of the impurity ionization energy, in particular, in HfO2. Our work demonstrates the importance of screening and polaronic effects on the transport properties in nanoscale devices based on Si nanowires

Domaines: Sciences de l'ingénieur [physics]

Mamadou Diarra, Christophe Delerue, Yann-Michel Niquet, Guy Allan. Screening and polaronic effects induced by a metallic gate and a surrounding oxide on donor and acceptor impurities in silicon nanowires. Journal of Applied Physics, 2008, 103, pp.073703-1-5. ⟨10.1063/1.2901182⟩. ⟨hal-00357380⟩