Task 2 Determine the Oxide Relative Permittivity (εr or k)

 The oxide relative permittivity can be calculated using the mathematical characteristics of capacitors under the accumulation region (which is the highest region of the C-V plot).

Under the accumulation condition, the MOS capacitor can be seen as the series connection of the Cox and Cacc.
          
As Cacc is exponentially dependent on
and therefore very large. (Cacc=dCacc/dΦS) 

So, in above equation, the term of accumulation capacitance can be ignored and the total capacitance can be seen equal to oxide capacitance.

Then we can obtain the oxide capacitance by reading the max value from the C-V plot, from given data, the value is 2.92E+03pF. Then we can calculate the oxide relative permittivity through function below:

With given data, we have:





By substituting equations 2.2 to 2.5 into equation 2.1, we obtained εox=6.8.







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