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361.

The process of adding impurity to a semi-conductor material is called

A.	Mixing	B.	Film deposition
C.	Binding	D.	Doping
E.	Grouping

362.

Which of the following is donor impurity for semi-conductors?

A.	Antimony	B.	Aluminium
C.	Boron	D.	Indium
E.	Callium

363.

Which of the following is 'acceptor' impurity for semi-conductor?

A.	Arsenic	B.	Phosphorous
C.	Boron	D.	Antimony
E.	All of the above

364.

when atoms are hold together by the sharing of valence electrons

A.	They form a covalent bond	B.	The valence electrons are free to move away from the atom
C.	Each shared electron leaves a hole	D.	Each atom becomes free to move
E.	None of the above

365.

When a normal atom loses an electron, the atom

A.	Becomes a positive ion	B.	Becomes a negative ion
C.	Becomes a electrically neutral	D.	Is then free to move about
E.	None of the above

366.

Eutectic is

A.	a phase transformation in which all the liquid phase transforms on cooling to two solid phases simultaneously	B.	A phase transformation which occurs above the glass transition temperature
C.	a solid solution of one component in another	D.	None of the above

367.

A non-crystalline polymer which can be stretched to more than twice its original length and which contracts quickly on releasing the load, is known as

A.	copolymer	B.	dilatant
C.	plastic	D.	elastomer

368.

Figure of merit is used to

A.	compare the efficiency of chermoelectric materials	B.	measure the extent of doping of intrinsic semi-conductors
C.	compare the extent of purity of semi-seonuctor materials	D.	None of the above

369.

When the temperature of a semi-conductor is reduced to absolute zero

A.	all electrons become free	B.	electrons move at higher velocities
C.	all valence electrons remain in the valence bond	D.	all valence electrons shift to forbidden gap

370.

Burger's vector is

A.	estimation of force9 of substit9utional atoms	B.	a defect in crystall structure
C.	a property of dislocations	D.	None of the above