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Worksheet-1 (Semiconductor Devices)


                1   In Conductor, Semiconductor and Insulator, the forbidden energy gap are E1 ,E2 and E3
                    respectively. Which one is correct
                    a) E1 <E2 < E3                                                                                   b) E1 >E2 = E3
                    c) E1 = E2 < E3                                                                                 d) E1 >E2 > E3
                2   Silicon is doped with which of the following to obtain P type semiconductor
                     a) Phosphorus                                             b) Gallium
                    c) Germanium                                              d) Bismuth
                3   What happens to resistance of an intrinsic semiconductor when heated
                    a) increase
                     b) remains constant
                     c) decreases
                    d) decreases linearly
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                4   A semiconductor has an electron concentration of 6 × 10 22  per m and hole concentration of 8.5
                        9
                    × 10  per m3 .Then it is
                    a) conductor
                     b) P type semi conductor
                    c) intrinsic semiconductor
                    d) N type semiconductor
                5   In an n-type silicon, which of the following statement is true :
                    (a) Electrons are majority carriers and trivalent atoms are the dopants.
                    (b) Electrons are minority carriers and pentavalent atoms are the dopants.
                    (c) Holes are minority carries and pentavalent atoms are the dopants.
                    (d) Holes are majority carries and trivalent atoms are the dopants.
                6   In an unbiased p-n junction, holes diffuse from the p-region to n-region because
                     (a) free electrons in the n-region attract them.
                    (b) they move across the junction by the potential difference.
                     (c) hole concentration in p-region is more as compared to n-region.
                     (d) All the above.
                7   When a forward bias is applied to a p-n junction, it
                     (a) raises the potential barrier.
                    (b) reduces the majority carrier current to zero.
                    (c) lowers the potential barrier.
                    (d) None of the above.
                8   In a p-type silicon, which of the following statement is true :
                    (a) Electrons are majority carriers and trivalent atoms are the dopants.
                     (b) Electrons are minority carriers and pentavalent atoms are the dopants.
                    (c) Holes are minority carries and pentavalent atoms are the dopants.
                    (d) Holes are majority carries and trivalent atoms are the dopants.
                9   Explain the processes involves in the formation of pn junction.
                10  Define depletion width and barrier potential in a.pn junction.
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