121. In p-type semiconductor :
(a) Holes form the majority carrier
(b) Free electrons form the minority carrier
(c) Hole density is equal to electron density
(d) It is formed by adding pentavalent impurity
122. In an intrinsic semiconductor, Fermi level represents the energy level with probability of its occupation of :
(a) 0 per cent
(b) 25 per cent
(c) 50 per cent
(d) 75 per cent
123. In germanium, medium doping corresponds to impurity of the order :
(a) 1 part in 105
(b) 1 part in 104
(c) 1 part in 103
(d) 1 part in102
124. Forbidden energy gap between the valence and conduction bands is least in the case of :
(a) Pure Si
(b) Pure Ge
(c) Mica
(d) Impure Si
125. Through repeated zone refining, the residual impurity in a semiconductor is of the order :
(a) 1 part in 104
(b) 1 part in 107
(c) 1 part in 109
(d) 1 part in1011
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- Semiconductor Materials » Exercise - 3148. At absolute temperature, an intrinsic semiconductor has ........ (a) a few free electrons (b) many holes (c) many free electrons (d) no holes or free electrons
- Semiconductor Materials » Exercise - 4153. In a substance the conduction band and valence band are separated by a energy gap of the order of 1 eV, and there are at room temperature as money electrons in the conduction band as holes in the valence band. The substance is : (a) An intrinsic semiconductor (b) A p-type semiconductor (c) A N-type semiconductor (d) A doped semiconductor