61. To make silicon P-type, one must add :
(a) Ge
(b) Si
(c) Sb
(d) Ga
62. An N-type semiconductor as a whole is :
(a) Positively charged
(b) Negatively charged
(c) Electrically neutral
(d) Canrsquo;t be defined
63. In an unbiased semiconductor junction, the junction current at equilibrium is :
(a) Zero because equal and opposite charges are crossing the junction
(b) Zero because no charges are crossing the junction
(c) Due to diffusion of minority carriers
(d) Due to diffusion of majority carriers
64. The depletion region is one which has :
(a) Immobile charges
(b) Mobile charges
(c) Atoms
(d) Molecules
65. Donor type impurities. i : Have five valence electrons. ii : Create excess free electrons. iii : Are used to make n-type semiconductors. iv : Have three valence electrons. Of these statements
(a) i and iv are correct
(b) i, ii and iii are correct
(c) ii, iii and iv are correct
(d) iii and iv are correct
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