The physical and electrical properties of a Ge/GeO2/HfO2/Al gate stack are investigated.A thin interfacial GeO2 layer（ 1 nm） is formed between Ge and HfO2 by dual ozone treatments,which passivates the Ge/high-k interface.Capacitors on p-type Ge substrates show very promising capacitance-voltage（C-V） characteristics by using in situ pre-gate ozone passivation and ozone ambient annealing after high-k deposition,indicating efficient passivation of the Ge/HfO2 interface.It is shown that the mid-gap interface state density at the Ge/GeO2 interface is 6.4×1011 cm-2·eV-1.In addition,the gate leakage current density of the Ge/GeO2/HfO2/Al gate stack passivated by the dual ozone treatments is reduced by about three orders of magnitude compared to that of a Ge/HfO2/Al gate stack without interface passivation.
In this paper, we report the fabrication, electrical and physical characteristics of TiN/HfO2/Si MOS capacitors with erbium (Er) ion implantation. It is demonstrated that the flat band voltage can be reduced by 0.4 V due to the formation of Er oxide. Moreover, it is observed that the equivalent oxide thickness is thinned down by 0.5 nm because the thickness of interfacial layer is significantly reduced, which is thought to be attributed to the strong binding capability of the implanted Er atoms with oxygen atoms. In addition, cross-sectional transmission electron microscopy experiment shows that the HfO2 layer with Er ion implantation is still amorphous after annealing at a high temperature. This Er ion implantation technique has the potential to be implemented as a band edge metal gate solution for NMOS without a capping layer, and may also satisfy the demand of the EOT reduction in 32 nm technology node.
A PNPN tunnel field effect transistor(TFET) with a high-k gate dielectric and a low-k fringe dielectric is introduced.The effects of the gate and fringe electric fields on the TFET’s performance were investigated through two-dimensional simulations.The results showed that a high gate dielectric constant is preferable for enhancing the gate control over the channel,while a low fringe dielectric constant is useful to increase the band-to-band tunneling probability.The TFET device with the proposed structure has good switching characteristics,enhanced on-state current,and high process tolerance.It is suitable for low-power applications and could become a potential substitute in next-generation complementary metal-oxide-semiconductor technology.
