We experimentally examine the effective mobility in nMOSFETs with La2O3 gate dielectrics without SiOx-based interfacial layer. The reduced mobility is mainly caused by fixed charges in High-k gate dielectrics and the contribution of the interface state density is approximately 30% at Ns = 5 × 1011 cm-2 in the low 1011 cm-2 eV-1 order. It is considered that one of the effective methods for improving mobility is to utilize La-silicate layer formed by high temperature annealing. However, there essentially exists trade-off relationship between high temperature annealing and small EOT.
- Direct contact
- Effective mobility