Task 2 and 3: Relative Permittivity and Equivalent Oxide Thickness

Relative Permittivity

From Task 1 we know that the when the gate is in accumulation condition, the total capacitance is 3000pF. Under this circumstance, the accumulation capacitor, C_SiO2 and C_High-k are in series. Due to a high value of accumulation capacitor, it could be ignored. Therefore, we deduced that C_max=C_SiO2||C_High-k. Since we also know that C=Aε₀ε_r/t, where t is the thickness of material; the only one unknown value is ε_High-k (ε_r). Hence we got ε_r is about 8.67.

Equivalent Oxide Thickness (EOT)

Once we knew the relative permittivity of High-k material, it was easier to determine EOT. According to the equation EOT=ε_SiO2*t_{High-k /}ε_r+t_SiO2, EOT can be calculated as 3.04nm.