1. Two identical silicon junction diodes, D1 and D2 are
connected
back to back as shown figure. The reverse saturation current ,
IS
of each diode is 10-8 amps and the breakdown voltage is
50 volts.
Evaluate the voltage VD1 and VD2 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, Ɛr
= 4, and Ɛo
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 :
ni = 1013
cm-3,
µn = 3500 cm2/V-sec,
µp
= 1500 cm2/V-sec,
KT/q = 26 mV.

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