GATE Electronics and Communications (EC) 2017 Shift 2 Solved Paper

A MOS capacitor is fabricated on p-type Si (Silicon) where the metal work function is 4.1 eV and electron affinity of Si is 4.0 eV. E_C - E_F = 0.9 eV, where E_C and E_F are the conduction band minimum and the Fermi energy levels of Si, respectively. Oxide ϵ_r = 3.9, ϵ_o = 8.85 × 10^-14 F/cm, oxide thickness t_ox = 0.1 μm and electronic charge q = 1.6 × 10^-19 C. If the measured flat band voltage of this capacitor is -1 V, then the magnitude of the fixed charge at the oxide-semiconductor interface, in nC/cm², is ________.