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 SiO

_{2}layer of 80 mm thickness,
under strong
accumulation. Assume the relative dielectric

constant of SiO

_{2}, 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 SiO

_{2}film is 10^{7}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}= 10^{13}cm^{-3},
µ

_{n}= 3500 cm^{2}/V-sec,
µ

_{p}= 1500 cm^{2}/V-sec,
KT/q = 26 mV.

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