University Solution 2011-12

ADVANCED SEMICONDUCTOR DEVICES

Ans 1a(i).In solid state physics, a particle's effective mass (often denoted m*) is the mass that it seems to have when responding to forces. One of the results from the band theory of solids is that the movement of particles in a periodic potential, over long distances larger than the lattice spacing, can be very different from their motion in a vacuum. The effective mass is a quantity that is used to simplify band structures by constructing an analogy to the behavior of a free particle with that mass.

Kinetic Energy of Holes

Ans 1a(ii)

ANS1(b)Excess Carrier Life Time

Ans 1(c)

Ans2(a)

Ans 2(b)

Ans 2(c )

Ans 3(a) Photo Diode: Working Principle

VI characteristics

Ans 3b Degenerate Semiconductors are the conductors whose Fermi Level lies within the conduction band or valence band

Tunnel diode is one of its type.

Working of tunnel diode

Ans 3(c) IMPATT Diode

IMPATT stands for impact ionization avalanche transit time.

It uses avalanche and carrier drift processes in a semiconductor to produce dynamic negative resistance at microwave frequencies.

Any p-n junction diode at avalanche breakdown can be used as an IMPATT diode

Ans 4(a)

VI characteristics

Ans 4(b)

Ans 4(c) Charge Coupled Devices