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00000EC203121902

cm?

+ compute the maximum electric field in the case of a junction formed by
these two materials at 300 K, when the applied reverse voltage is 57. Compute
the junction capacitance per unit area for this case. Assume that Si is doped with
10'/em? n type dopants.

With suitable energy band diagram explain a Schottky contact.

Differentiate between Zener and avalanche breakdown mechanisms with
supporting diagrams
Draw the energy band diagram of a p-n junction at a) equilibrium b) Forward
bias c) Reverse bias.
PART ட்‌

Answer any two full questions, each carries 20 marks.
Derive an expression for base transport factor of a BJT.
Explain Early effect.

A pnp BJT has emitter (Ng), base (Ng), and collector (Nc) doping of 107? का,
107 cm > and 1011 ला > respectively, and a base width of 0.5 micron. Calculate
the peak electric field at the CB junction, and the CB depletion capacitance per
unit area for the normal active mode of operation with a ५८४ = 50 ५.

Draw and explain the C-V Characteristics of an Ideal MOS capacitor. Derive the
expression for threshold voltage.

For a MOSFET with Vr ಎ 1V and W = 50 um, L ಎ 2 unm, calculate the drain
current at

(i) Vo = 5 ४, Vp =0.1V

(ii) ४७८३४, ४७८5५.

Assume an electron channel 71001119 [൧ 0 cm? /V-s, gate oxide thickness
tox= 100A, and the substrate is connected to the source.

Draw and explain the subthreshold characteristics of an n-channel MOSFET.

With the aid of necessary band diagrams, explain equilibrium, accumulation,
depletion and inversion stages of a MOS capacitor.
Explain the effect of real surfaces in the threshold voltage of a MOS capacitor.

Explain the terms emitter injection efficiency and base transport factor of a BJT.

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