## Tuesday, 11 June 2013

### 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 ,

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. 