A MOS capacitor is fabricated by using Metal layer deposited on top of 20 nm thick SiO2 oxide layer on top of p-type silicon with doping concentration of NA = 1×1014 cm−3. Dielectric coefficients of silicon and oxide layer is given as KS = 11.8, KO = 3.9, ε0 = 8.86×10−14 F/cm. Calculate the threshold voltage required to create inversion layer. (Assume flat band approximation is valid).