Video Solutions for GATE 1995 ECE : Five Mark Questions ( Electron Devices )

1. Two identical silicon junction diodes, D1 and D2 are connected 

    back to back as shown figure. The reverse saturation current ,

    I_S of each diode is 10^-8 amps and the breakdown voltage is 

    50 volts. 

    Evaluate the voltage V_D1 and V_D2 across the diode D1 and D2

    by assuming KT/q to be 25mV.

 

2. Calculate the capacitance of a circular MOS capacitor, 

    of 0.5 mm dia and having a SiO₂ layer of 80 mm thickness, 

    under strong accumulation. Assume the relative dielectric 

    constant of SiO₂, Ɛ_r = 4, and Ɛ_o to be 8.854x10^-14 F/cm. 

    Calculate the break down voltage of the capacitor if the 

    dielectric strength of SiO₂ film is 10⁷ V/cm.

 

3. The Fermi level of an n-type Germanium film is 0.2 eV above

    the intrinsic Fermi level towards the conduction band. 

    The thickness of the film is 0.5 µm. Calculate the sheet

     resistance of the film.

     Assume :

     n_i = 10¹³ cm^-3,  

     µ_n = 3500 cm²/V-sec,

     µ_p = 1500 cm²/V-sec,

     KT/q = 26 mV.