155. In a p-typeisemiconductor, as the donor concentration No is increased, the fermi level
A. remained unaltered
B. moves toward the valence band
C. moves toward the centre of forbidden band
D. may nor may not move depending on the temperature

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156. In a semiconductor, the hole diffusion current is proportional to dp where p is the hole concentration and 4 is the applied electric field
A. dx
B. d2p
C. e
D.2

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157. In a semiconductor, the ratio of diffusion constant to mobility for a hole is proportional to where T is the temperature index K.
A. T
B. T2
C. I/T
D. I /T2

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158. The diffusion length Lp for hole in a semiconductor equals where D is the diffusion constant for hole and is the mean lifetime of hole
A. D T
B. (Dt)2P P
C. FITTr,
D. Dpitp

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159. In a graded semiconductor, potential of point concentration p2 and pi respectively equals P2
A. VT In (?Pi(TE)
B. VTIn NAND
C. ?vT InN,2 N
D. (? ?P2PI

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160.  In an open curcuited step graded p-n junction having donor concentration ND and acceptor concentration NA, the contact difference of potential developed is carriers are the
A.
B.
C.
D.

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161. Injected minority minority carriers which
A. are in excess of the number of majority carriers
B. are impurity generated
C. are thermally generated
D. are in excess of the equilibrium number

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