| Autor: |
Miyata, Noriyuki, Yasuda, Tetsuji, Abe, Yasuhiro |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; Oct2011, Vol. 110 Issue 7, p074115, 8p |
| Abstrakt: |
Although the direct-contact HfO2/Si structure has been demonstrated to have advantages on an equivalent oxide thickness scaling of <1 nm, characteristic electric charges have been reported to be formed at the HfO2/Si interface. A Kelvin probe method was used to examine the electric charges in HfO2/Si structures. We first describe the basic principles behind the Kelvin probe measurements of electric charges in an oxide/Si structure, and then point out what effect the surface adsorbates have on the measured contact-potential-difference voltage (VCPD). A large VCPD difference (>0.5 V) was observed between the direct-contact HfO2/Si and HfO2/SiO2/Si stack surfaces, which suggests the existence of a strong interface dipole. This result is consistent with previous reports using electrical measurements of metal-oxide-semiconductor capacitances. We also found that the dipole completely disappeared after ultrahigh vacuum annealing at 700 °C, and appeared again after exposure to O2 at room temperature. The formation of a dipole by exposure to O2 had a correlation with the formation of Si-O bonds at the HfO2/Si interface. We propose that interface Si-O-Hf bonding naturally produces a strong interface dipole from simple electrostatic potential analysis mainly due to the effect of the large dielectric constant of HfO2. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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