JEE Main & Advanced Physics Semiconducting Devices Question Bank

done Semiconductors Total Questions - 101

• question_answer1)
  The majority charge carriers in P-type semiconductor are  [MP PMT 1999; CBSE PMT 1999; MP PET 1991; MP PET/PMT 1998; MH CET 2003]
  A)
             Electrons                                done clear
  B)
             Protons done clear
  C)
             Holes                                        done clear
  D)
             Neutrons done clear
  View Solution play_arrow

• question_answer2)
  A P-type semiconductor can be obtained by adding  [NCERT 1979; BIT 1988; MP PMT 1987; 90]
  A)
             Arsenic to pure silicon done clear
  B)
             Gallium to pure silicon done clear
  C)
             Antimony to pure germanium done clear
  D)
             Phosphorous to pure germanium done clear
  View Solution play_arrow

• question_answer3)
  The valence of an impurity added to germanium crystal in order to convert it into a P-type semi conductor is [MP PMT 1989; CPMT 1987]
  A)
             6     done clear
  B)
             5 done clear
  C)
             4     done clear
  D)
             3 done clear
  View Solution play_arrow

• question_answer4)
  In a semiconductor, the concentration of electrons is \[8\times {{10}^{14}}/c{{m}^{3}}\]and that of the holes is \[5\times {{10}^{12}}c{{m}^{3}}.\] The semiconductor  is [MP PMT 1997; RPET 1999; Kerala PET 2002]
  A)
             P-type                                     done clear
  B)
             N-type done clear
  C)
             Intrinsic                                   done clear
  D)
             PNP-type done clear
  View Solution play_arrow

• question_answer5)
  In P-type semiconductor, there is                    [MP PMT 1989]
  A)
             An excess of one electron done clear
  B)
             Absence of one electron done clear
  C)
             A missing atom done clear
  D)
             A donar level done clear
  View Solution play_arrow

• question_answer6)
  The valence of the impurity atom that is to be added to germanium crystal so as to make it a N-type semiconductor, is  [MNR 1993; MP PET 1994; CBSE PMT 1999; AIIMS 2000]
  A)
             6     done clear
  B)
             5 done clear
  C)
             4     done clear
  D)
             3 done clear
  View Solution play_arrow

• question_answer7)
  Silicon is a semiconductor. If a small amount of As is added to it, then its electrical conductivity [MP PMT 1996]
  A)
             Decreases                              done clear
  B)
             Increases done clear
  C)
             Remains unchanged          done clear
  D)
             Becomes zero done clear
  View Solution play_arrow

• question_answer8)
  When the electrical conductivity  of a semi-  conductor  is due to the breaking of its covalent bonds, then the semiconductor is said to be [AIIMS 1997; KCET (Engg.) 2002]
  A)
             Donar                                       done clear
  B)
             Acceptor done clear
  C)
             Intrinsic                                   done clear
  D)
             Extrinsic done clear
  View Solution play_arrow

• question_answer9)
  A piece of copper and the other of germanium are cooled from the room temperature to 80 K, then which of the following would be a correct statement  [IIT-JEE 1988; Bihar CEE 1992; CBSE PMT 1993; MP PET 1997; RPET 1999; AIEEE 2004]
  A)
             Resistance of each increases done clear
  B)
             Resistance of each decreases done clear
  C)
             Resistance of copper increases while that of germanium decreases done clear
  D)
             Resistance of copper decreases while that of germanium increases done clear
  View Solution play_arrow

• question_answer10)
  To obtain P-type \[Si\] semiconductor, we need to dope pure \[Si\] with                 [IIT-JEE 1988; MP PET 1997, 93; Pb. PMT 2001, 02; UPSEAT 2004]
  A)
             Aluminium                             done clear
  B)
             Phosphorous done clear
  C)
             Oxygen                                   done clear
  D)
             Germanium done clear
  View Solution play_arrow

• question_answer11)
  Electrical conductivity of a semiconductor  [MP PMT 1993, 2000; RPET 1996]
  A)
             Decreases with the rise in its temperature done clear
  B)
             Increases with the rise in its temperature done clear
  C)
             Does not change with the rise in its temperature done clear
  D)
             First increases and then decreases with the rise in its temperature done clear
  View Solution play_arrow

• question_answer12)
  Three semi-conductors are arranged in the increasing order of their energy gap as follows. The correct  arrangement is [MP PMT 1993]
  A)
             Tellurium, germanium, silicon done clear
  B)
             Tellurium, silicon, germanium done clear
  C)
             Silicon, germanium, tellurium done clear
  D)
             Silicon, tellurium, germanium done clear
  View Solution play_arrow

• question_answer13)
  When a semiconductor is heated, its resistance [KCET 1992; MP PMT 1994; MP PET 1992, 2002;  RPMT 2001; DCE 2001]
  A)
             Decreases                              done clear
  B)
             Increases done clear
  C)
             Remains unchanged          done clear
  D)
             Nothing is definite done clear
  View Solution play_arrow

• question_answer14)
  In an insulator, the forbidden energy gap between the valence band and conduction band is of the order of       [DPMT 1988; EAMCET (Engg.) 1995; MP PET 1996]
  A)
             \[1\,MeV\]                            done clear
  B)
             \[0.1\,MeV\] done clear
  C)
             \[1\,eV\]                                done clear
  D)
             \[5\,eV\] done clear
  View Solution play_arrow

• question_answer15)
   A N-type semiconductor is                           [AFMC 1988; RPMT 1999]
  A)
             Negatively charged            done clear
  B)
             Positively charged done clear
  C)
             Neutral                                    done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer16)
  The energy band gap of \[Si\] is [MP PET 1994, 2002; BHU 1995; RPMT 2000]
  A)
             \[0.70\,eV\] done clear
  B)
             1.1 eV done clear
  C)
             Between \[0.70\,eV\] to \[1.1\,eV\] done clear
  D)
             5 eV done clear
  View Solution play_arrow

• question_answer17)
  The forbidden energy band gap in conductors, semiconductors and insulators are \[E{{G}_{1}},\,E{{G}_{2}}\]and \[E{{G}_{3}}\] respectively. The relation among them is [MP PMT 1994; RPMT 1997]
  A)
             \[E{{G}_{1}}=E{{G}_{2}}=E{{G}_{3}}\]                            done clear
  B)
             \[E{{G}_{1}}<E{{G}_{2}}<E{{G}_{3}}\] done clear
  C)
             \[E{{G}_{1}}>E{{G}_{2}}>E{{G}_{3}}\]                            done clear
  D)
             \[E{{G}_{1}}<E{{G}_{2}}>E{{G}_{3}}\] done clear
  View Solution play_arrow

• question_answer18)
  Which statement is correct                                             [MP PMT 1994]
  A)
             N-type germanium is negatively charged and P-type germanium is positively charged done clear
  B)
             Both N-type and P-type germanium are neutral done clear
  C)
             N-type germanium is positively charged and P-type germanium is negatively charged done clear
  D)
             Both N-type and P-type germanium are negatively charged done clear
  View Solution play_arrow

• question_answer19)
  When Ge crystals are doped with phosphorus atom, then it becomes       [AFMC 1995; Orissa PMT 2004]
  A)
             Insulator                                 done clear
  B)
             P-type done clear
  C)
             N-type                                     done clear
  D)
             Superconductor done clear
  View Solution play_arrow

• question_answer20)
  Let \[{{n}_{P}}\] and \[{{n}_{e}}\] be the number of holes and conduction electrons respectively in a semiconductor. Then [MP PET 1995]
  A)
             \[{{n}_{P}}>{{n}_{e}}\]in an intrinsic semiconductor done clear
  B)
             \[{{n}_{P}}={{n}_{e}}\]in an extrinsic semiconductor done clear
  C)
             \[{{n}_{P}}={{n}_{e}}\]in an intrinsic semiconductor done clear
  D)
             \[{{n}_{e}}>{{n}_{P}}\]in an intrinsic semiconductor done clear
  View Solution play_arrow

• question_answer21)
  Wires P and Q have the same resistance at ordinary (room) temperature. When heated, resistance of \[P\] increases and that of Q decreases. We conclude that [MP PMT 1995; MP PET 2001]
  A)
             P and Q are conductors of different materials done clear
  B)
             P is N-type semiconductor and Q is P-type semiconductor done clear
  C)
             P is semiconductor and Q is conductor done clear
  D)
             P is conductor and Q is semiconductor done clear
  View Solution play_arrow

• question_answer22)
  The impurity atoms which are mixed with pure silicon to make a P-type semiconductor are those of  [MP PMT 1995]
  A)
             Phosphorus                           done clear
  B)
             Boron done clear
  C)
             Antimony                               done clear
  D)
             Copper done clear
  View Solution play_arrow

• question_answer23)
  Holes are charge carriers in                                                   [IIT-JEE 1996]
  A)
             Intrinsic semiconductors  done clear
  B)
             Ionic solids done clear
  C)
             P-type semiconductors    done clear
  D)
             Metals done clear
  View Solution play_arrow

• question_answer24)
  In extrinsic P and N-type, semiconductor materials, the ratio of the impurity atoms to the pure semiconductor atoms is about                                                                                    [MP PET 2003]
  A)
             1     done clear
  B)
             \[{{10}^{-1}}\] done clear
  C)
             \[{{10}^{-4}}\]                      done clear
  D)
             \[{{10}^{-7}}\] done clear
  View Solution play_arrow

• question_answer25)
  A hole in a P-type semiconductor is                    [MP PET 1996]
  A)
             An excess electron             done clear
  B)
             A missing electron              done clear
  C)
             A missing atom                         done clear
  D)
             A donor level done clear
  View Solution play_arrow

• question_answer26)
  The forbidden gap in the energy bands of germanium at room temperature is about  [MP PMT/PET 1998]
  A)
             \[1.1eV\]                                done clear
  B)
             \[0.1eV\] done clear
  C)
             \[0.67eV\]                              done clear
  D)
             \[6.7eV\] done clear
  View Solution play_arrow

• question_answer27)
  In P-type semiconductor the majority and minority charge carriers are respectively [EAMCET 1994; MP PMT/PET 1998; MH CET 2000]
  A)
             Protons and electrons      done clear
  B)
             Electrons and protons done clear
  C)
             Electrons and holes            done clear
  D)
             Holes and electrons done clear
  View Solution play_arrow

• question_answer28)
  At zero Kelvin a piece of germanium                  [MP PET 1999]
  A)
             Becomes semiconductor done clear
  B)
             Becomes good conductor done clear
  C)
             Becomes bad conductor  done clear
  D)
             Has maximum conductivity done clear
  View Solution play_arrow

• question_answer29)
  Electronic configuration of germanium is 2, 8, 18 and 4. To make it extrinsic semiconductor small quantity of antimony is added                                                                                     [MP PET 1999]
  A)
             The material obtained will be N-type germanium in which electrons and holes are equal in number done clear
  B)
             The material obtained will be P-type germanium done clear
  C)
             The material obtained will be N-type germanium which has more electrons than holes at room temperature done clear
  D)
             The material obtained will be N-type germanium which has less electrons than holes at room temperature done clear
  View Solution play_arrow

• question_answer30)
  A semiconductor is cooled from \[{{T}_{1}}K\] to \[{{T}_{2}}K.\] Its resistance [MP PET 1999]
  A)
             Will decrease done clear
  B)
             Will increase done clear
  C)
             Will first decrease and then increase done clear
  D)
             Will not change done clear
  View Solution play_arrow

• question_answer31)
  If \[{{N}_{P}}\]and \[{{N}_{e}}\]be the numbers of holes and conduction electrons in an extrinsic semiconductor, then [MP PMT 1999; AMU 2001]
  A)
             \[{{N}_{P}}>{{N}_{e}}\] done clear
  B)
             \[{{N}_{P}}={{N}_{e}}\] done clear
  C)
             \[{{N}_{P}}<{{N}_{e}}\] done clear
  D)
             \[{{N}_{P}}>{{N}_{e}}\] or \[{{N}_{P}}<{{N}_{e}}\] depending on the nature of impurity  done clear
  View Solution play_arrow

• question_answer32)
  In intrinsic semiconductor at room temperature, number of electrons and holes are [EAMCET (Engg.) 1995; JIPMER 2001, 02]
  A)
             Equal                                        done clear
  B)
             Zero done clear
  C)
             Unequal                                  done clear
  D)
             Infinite done clear
  View Solution play_arrow

• question_answer33)
  (USS 133) Indium impurity in germanium makes [EAMCET (Engg.) 1995]
  A)
             N-type                                     done clear
  B)
             P-type done clear
  C)
             Insulator                                 done clear
  D)
             Intrinsic done clear
  View Solution play_arrow

• question_answer34)
  Fermi level of energy of an intrinsic semiconductor lies [EAMCET (Med.) 1995]
  A)
             In the middle of forbidden gap done clear
  B)
             Below the middle of forbidden gap done clear
  C)
             Above the middle of forbidden gap done clear
  D)
             Outside the forbidden gap done clear
  View Solution play_arrow

• question_answer35)
  In a semiconductor the separation between conduction band and valence band is of the order of [EAMCET (Med.) 1995; AIIMS 2000]
  A)
             \[100\,eV\]                            done clear
  B)
             \[10\,eV\] done clear
  C)
             \[1\,eV\]                                done clear
  D)
             0 eV done clear
  View Solution play_arrow

• question_answer36)
  The intrinsic semiconductor becomes an insulator at [EAMCET (Med.) 1995; KCET (Engg./Med.) 1999;  MP PET 2000; CBSE PMT 2001]
  A)
             \[0{}^\circ C\]                       done clear
  B)
             \[-100{}^\circ C\] done clear
  C)
             \[300\ K\]                               done clear
  D)
             \[0\ K\] done clear
  View Solution play_arrow

• question_answer37)
  The addition of antimony atoms to a sample of intrinsic germanium transforms it to a material which is [AMU 1995]
  A)
             Superconductor                  done clear
  B)
             An insulator done clear
  C)
             N-type semiconductor     done clear
  D)
             P-type semiconductor done clear
  View Solution play_arrow

• question_answer38)
  Resistance of semiconductor at \[0{}^\circ K\] is [RPET 1997]
  A)
             Zero                                          done clear
  B)
             Infinite done clear
  C)
             Large                                        done clear
  D)
             Small done clear
  View Solution play_arrow

• question_answer39)
  In a good conductor the energy gap between the conduction band and the valence band is [KCET 1993; EMCET (Med.) 1994]
  A)
             Infinite                                    done clear
  B)
             Wide done clear
  C)
             Narrow                                    done clear
  D)
             Zero done clear
  View Solution play_arrow

• question_answer40)
  The impurity atom added to germanium to make it N-type semiconductor is          [KCET 1993; KCET (Engg./Med.) 2000]
  A)
             Arsenic                                    done clear
  B)
             Iridium done clear
  C)
             Aluminium                             done clear
  D)
             Iodine done clear
  View Solution play_arrow

• question_answer41)
  When N-type of semiconductor is heated [CBSE PMT 1993; DPMT 2000]
  A)
             Number of electrons increases while that of holes decreases done clear
  B)
             Number of holes increases while that of electrons decreases done clear
  C)
             Number of electrons and holes remains same done clear
  D)
             Number of electrons and holes increases equally done clear
  View Solution play_arrow

• question_answer42)
  To obtain a P-type germanium semiconductor, it must be doped with       [CBSE PMT 1997; Pb. PET 2000]
  A)
             Arsenic                                    done clear
  B)
             Antimony done clear
  C)
             Indium                                     done clear
  D)
             Phosphorus done clear
  View Solution play_arrow

• question_answer43)
  The temperature coefficient of resistance of a semiconductor  [AFMC 1998, MNR 1998]
  A)
             Is always positive                done clear
  B)
             Is always negative done clear
  C)
             Is zero done clear
  D)
             May be positive or negative or zero done clear
  View Solution play_arrow

• question_answer44)
  P-type semiconductor is formed when                 [RPET 1999]            A.   As impurity is mixed in Si            B.    Al impurity is mixed in Si            C.    B impurity is mixed in Ge            D.   P impurity is mixed in Ge
  A)
             A and C                                    done clear
  B)
             A and D done clear
  C)
             B and C                                    done clear
  D)
             B and D done clear
  View Solution play_arrow

• question_answer45)
  In case of a semiconductor, which of the following statement is wrong                                                 [Pb. PMT 1999]
  A)
             Doping increases conductivity done clear
  B)
             Temperature coefficient of resistance is negative done clear
  C)
             Resisitivity is in between that of a conductor and insulator done clear
  D)
             At absolute zero temperature, it behaves like a conductor done clear
  View Solution play_arrow

• question_answer46)
  Energy bands in solids are a consequence of  [DCE 1999, 2000; AIEEE 2004]
  A)
             Ohm?s Law done clear
  B)
             Pauli?s exclusion principle done clear
  C)
             Bohr?s theory done clear
  D)
             Heisenberg?s uncertainty principle done clear
  View Solution play_arrow

• question_answer47)
  In a P-type semiconductor  [AIIMS 1997; Orissa JEE 2002; MP PET 2003]
  A)
             Current is mainly carried by holes done clear
  B)
             Current is mainly carried by electrons done clear
  C)
             The material is always positively charged done clear
  D)
             Doping is done by pentavalent material done clear
  View Solution play_arrow

• question_answer48)
  At ordinary temperatures, the electrical conductivity of semi conductors in \[mho/mete\text{r}\] is in the range [MP PET 2003]
  A)
             \[{{10}^{-3}}\] to \[{{10}^{-4}}\]                                       done clear
  B)
             \[{{10}^{6}}\text{ to }{{10}^{9}}\] to \[{{10}^{9}}\] done clear
  C)
             \[{{10}^{-6}}\] to \[{{10}^{-10}}\]                                     done clear
  D)
             \[{{10}^{-10}}\] to \[{{10}^{-16}}\] done clear
  View Solution play_arrow

• question_answer49)
  When the temperature of silicon sample is increased from \[27{}^\circ C\] to \[100{}^\circ C\], the conductivity of silicon will be  [RPMT 1999]
  A)
             Increased                               done clear
  B)
             Decreased done clear
  C)
             Remain same                        done clear
  D)
             Zero done clear
  View Solution play_arrow

• question_answer50)
  In a P-type semiconductor, germanium is doped with [AFMC 1999]
  A)
             Boron                                       done clear
  B)
             Gallium done clear
  C)
             Aluminium done clear
  D)
             All of these done clear
  View Solution play_arrow

• question_answer51)
  In N-type semiconductors, majority charge carriers are [AIIMS 1999]
  A)
             Holes                                        done clear
  B)
             Protons done clear
  C)
             Neutrons                                done clear
  D)
             Electrons done clear
  View Solution play_arrow

• question_answer52)
  Semiconductor is damaged by the strong current due to [MH CET 2000]
  A)
             Lack of free electron         done clear
  B)
             Excess of electrons done clear
  C)
             Excess of proton                 done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer53)
  GaAs is                                                       [RPMT 2000]
  A)
             Element semiconductor done clear
  B)
             Alloy semiconductor done clear
  C)
             Bad conductor done clear
  D)
             Metallic semiconductor done clear
  View Solution play_arrow

• question_answer54)
  If \[{{n}_{e}}\] and \[{{n}_{h}}\] are the number of electrons and holes in a semiconductor heavily doped with phosphorus, then  [MP PMT 2000]
  A)
             \[{{n}_{e}}>>{{n}_{h}}\] done clear
  B)
             \[{{n}_{e}}<<{{n}_{h}}\] done clear
  C)
             \[{{n}_{e}}\le {{n}_{h}}\] done clear
  D)
             \[{{n}_{e}}={{n}_{h}}\] done clear
  View Solution play_arrow

• question_answer55)
  An N-type and P-type silicon can be obtained by doping pure silicon with                                              [EAMCET (Med.) 2000]
  A)
             Arsenic and Phosphorous       done clear
  B)
             Indium and Aluminium done clear
  C)
             Phosphorous and Indium        done clear
  D)
             Aluminium and Boron done clear
  View Solution play_arrow

• question_answer56)
  N-type semiconductors will be obtained, when germanium is doped with                                            [AIIMS 2000]
  A)
             Phosphorus                           done clear
  B)
             Aluminium done clear
  C)
             Arsenic                                    done clear
  D)
             Both (a) or (c) done clear
  View Solution play_arrow

• question_answer57)
  The state of the energy gained by valance electrons when the temperature is raised or when electric field is applied is called as                                                     [CBSE PMT 2000]
  A)
             Valance band                        done clear
  B)
             Conduction band done clear
  C)
             Forbidden band                   done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer58)
  To obtain electrons as majority charge carriers in a semiconductor, the impurity mixed is               [MP PET 2000]
  A)
             Monovalent                          done clear
  B)
             Divalent done clear
  C)
             Trivalent                                 done clear
  D)
             Pentavalent done clear
  View Solution play_arrow

• question_answer59)
  For germanium crystal, the forbidden energy gap in joules is       [MP PET 2000]
  A)
             \[1.12\times {{10}^{-19}}\]     done clear
  B)
             \[1.76\times {{10}^{-19}}\] done clear
  C)
             \[1.6\times {{10}^{-19}}\]       done clear
  D)
             Zero done clear
  View Solution play_arrow

• question_answer60)
  A pure semiconductor behaves slightly as a conductor at  [MH CET (Med.) 2001; BHU 2000; AFMC 2001]
  A)
             Room temperature            done clear
  B)
             Low temperature done clear
  C)
             High temperature               done clear
  D)
             Both (b) and (c) done clear
  View Solution play_arrow

• question_answer61)
  Which is the correct relation for forbidden energy gap in conductor, semi conductor and insulator [RPMT 2001; AIEEE 2002]
  A)
             \[\Delta E{{g}_{\text{c}}}>\Delta E{{g}_{\text{sc}}}>\Delta E{{g}_{\text{insulator}}}\] done clear
  B)
             \[\Delta E{{g}_{\text{insulator}}}>\Delta E{{g}_{\text{sc}}}>\Delta E{{g}_{\text{conductor}}}\] done clear
  C)
             \[\Delta E{{g}_{\text{conductor}}}>\Delta E{{g}_{\text{insulator}}}>\Delta E{{g}_{\text{sc}}}\] done clear
  D)
             \[\Delta E{{g}_{\text{sc}}}>\Delta E{{g}_{\text{conductor}}}>\Delta E{{g}_{\text{insulator}}}\] done clear
  View Solution play_arrow

• question_answer62)
  The band gap in Germanium and silicon in eV respectively is                                                        [MP PMT 2001]
  A)
             0.7, 1.1                                     done clear
  B)
             1.1, 0.7 done clear
  C)
             1.1, 0                                        done clear
  D)
             0, 1.1 done clear
  View Solution play_arrow

• question_answer63)
  P-type semiconductors are made by adding impurity element                                    [MP PMT 2001]
  A)
             As   done clear
  B)
             P done clear
  C)
             B     done clear
  D)
             Bi done clear
  View Solution play_arrow

• question_answer64)
  At room temperature, a P-type semiconductor has [Kerala PMT 2002]
  A)
             Large number of holes and few electrons done clear
  B)
             Large number of free electrons and few holes done clear
  C)
             Equal number of free electrons and holes done clear
  D)
             No electrons or holes done clear
  View Solution play_arrow

• question_answer65)
  In intrinsic semiconductor at room temperature, number of electrons and holes are [JIPMER 2001, 02; MP PMT 2002]
  A)
             Unequal                                  done clear
  B)
             Equal done clear
  C)
             Infinite                                    done clear
  D)
             Zero done clear
  View Solution play_arrow

• question_answer66)
  The valence band and conduction band of a solid overlap at low temperature, the solid may be [Orissa JEE 2002; BCECE 2004]
  A)
             A metal                                   done clear
  B)
             A semiconductor done clear
  C)
             An insulator                           done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer67)
  Which impurity is doped in Si to form N-type semi-conductor?   [CBSE PMT 1996; AIEEE 2002]
  A)
             Al    done clear
  B)
             B done clear
  C)
             As   done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer68)
  In a semiconductor                                   [AIEEE 2002; AIIMS 2002]
  A)
             There are no free electrons at any temperature done clear
  B)
             The number of free electrons is more than that in a conductor done clear
  C)
             There are no free electrons at 0 K done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer69)
  The energy band gap is maximum in                     [AIEEE 2002]
  A)
             Metals                                     done clear
  B)
             Superconductors done clear
  C)
             Insulators                               done clear
  D)
             Semiconductors done clear
  View Solution play_arrow

• question_answer70)
  The process of adding impurities to the pure semiconductor is called                                      [MH CET 2002]
  A)
             Drouping                                done clear
  B)
             Drooping done clear
  C)
             Doping                                     done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer71)
  When phosphorus and antimony are mixed in zermaniun, then                                                 [CPMT 2003]
  A)
             P-type semiconductor is formed done clear
  B)
             N-type semiconductor is formed done clear
  C)
             Both (a) and (b) done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer72)
  To a germanium sample, traces of gallium are added as an impurity. The resultant sample would behave like      [AIIMS 2003]
  A)
             A conductor done clear
  B)
             A P-type semiconductor done clear
  C)
             An N-type semiconductor done clear
  D)
             An insulator done clear
  View Solution play_arrow

• question_answer73)
  For non-conductors, the energy gap is  [EAMCET (Engg.) 1995; MP PET 1996; RPET 2003]
  A)
             6 eV                                          done clear
  B)
             1.1 eV done clear
  C)
             0.8 eV                                       done clear
  D)
             0.3 eV done clear
  View Solution play_arrow

• question_answer74)
  Donor type impurity is found in                                [RPET 2003]
  A)
             Trivalent elements             done clear
  B)
             Pentavalent elements done clear
  C)
             In both the above               done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer75)
  The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the                            [AIEEE 2003]
  A)
             Variation of scattering mechanism with temperature done clear
  B)
             Crystal structure done clear
  C)
             Variation of the number of charge carriers with temperature done clear
  D)
             Type of bon done clear
  View Solution play_arrow

• question_answer76)
  The charge on a hole is equal to the charge of [MP PMT 2004]
  A)
             Zero                                          done clear
  B)
             Proton done clear
  C)
             Neutron                                  done clear
  D)
             Electron done clear
  View Solution play_arrow

• question_answer77)
  When germanium is doped with phosphorus, the doped material has                                    [MP PMT 2004]
  A)
              Excess positive charge done clear
  B)
              Excess negative charge done clear
  C)
              More negative current carriers done clear
  D)
              More positive current carriers done clear
  View Solution play_arrow

• question_answer78)
  A Ge specimen is doped with Al. The concentration of acceptor atoms is ~1021 atoms/m3. Given that the intrinsic concentration of electron hole pairs is \[\tilde{\ }{{10}^{19}}/{{m}^{3}}\], the concentration of electrons in the specimen is                    [AIIMS 2004]
  A)
             \[{{10}^{17}}/{{m}^{3}}\] done clear
  B)
             \[{{10}^{15}}/{{m}^{3}}\] done clear
  C)
             \[{{10}^{4}}/{{m}^{3}}\]   done clear
  D)
             \[{{10}^{2}}/{{m}^{3}}\] done clear
  View Solution play_arrow

• question_answer79)
  Which of the following has negative temperature coefficient of resistance                                           [AFMC 2004]
  A)
             Copper                                    done clear
  B)
             Aluminium done clear
  C)
             Iron                                           done clear
  D)
             Germanium done clear
  View Solution play_arrow

• question_answer80)
  In semiconductors at a room temperature [CBSE PMT 2004]
  A)
             The valence band is partially empty and the conduction band is partially filled done clear
  B)
             The valence band is completely filled and the conduction band is partially filled done clear
  C)
             The valence band is completely filled done clear
  D)
             The conduction band is completely empty done clear
  View Solution play_arrow

• question_answer81)
  Regarding a semiconductor which one of the following is wrong                                                [CPMT 2004]
  A)
             There are no free electrons at room temperature done clear
  B)
             There are no free electrons at 0 K done clear
  C)
             The number of free electrons increases with rise of temperature done clear
  D)
             The charge carriers are electrons and holes done clear
  View Solution play_arrow

• question_answer82)
  Which of the following statements is true for an N-type semi-conductor                                               [CPMT 2004]
  A)
             The donor level lies closely below the bottom of the conduction band done clear
  B)
             The donor level lies closely above the top of the valence band done clear
  C)
             The donor level lies at the halfway mark of the forbidden energy gap done clear
  D)
             None of above done clear
  View Solution play_arrow

• question_answer83)
  Choose the correct statement                                                                   [DCE 2004]
  A)
             When we heat a semiconductor its resistance increases done clear
  B)
             When we heat a semiconductor its resistance decreases done clear
  C)
             When we cool a semiconductor to 0 K then it becomes super conductor done clear
  D)
             Resistance of a semiconductor is independent of temperature done clear
  View Solution play_arrow

• question_answer84)
  In a P-type semi-conductor, germanium is dopped with  [MH CET 2003]
  A)
             Gallium                                    done clear
  B)
             Boron done clear
  C)
             Aluminium                             done clear
  D)
             All of these done clear
  View Solution play_arrow

• question_answer85)
  A piece of semiconductor is connected in series in an electric circuit. On increasing the temperature, the current in the circuit will                                                                          [RPMT 2003]
  A)
             Decrease                                done clear
  B)
             Remain unchanged done clear
  C)
             Increase                                  done clear
  D)
             Stop flowing done clear
  View Solution play_arrow

• question_answer86)
  Intrinsic semiconductor is electrically neutral. Extrinsic semiconductor having large number of current carriers would be                                                                       [AMU (Engg.) 2001]
  A)
             Positively charged done clear
  B)
             Negatively charged done clear
  C)
             Positively charged or negatively charged depending upon the type of impurity that has been added done clear
  D)
             Electrically neutral done clear
  View Solution play_arrow

• question_answer87)
  If ne and vd be the number of electrons and drift velocity in a semiconductor. When the temperature is increased [Pb. CET 2000]
  A)
             ne increases and vd decreases                                           done clear
  B)
             ne decreases and vd increases                                           done clear
  C)
             Both ne and vd increases          done clear
  D)
             Both ne and vd decreases done clear
  View Solution play_arrow

• question_answer88)
  In extrinsic semiconductors                       [EAMCET (Engg.) 1999]
  A)
             The conduction band and valence band overlap done clear
  B)
             The gap between conduction band and valence band is more than 16 eV done clear
  C)
             The gap between conduction band and valence band is near about 1 eV done clear
  D)
             The gap between conduction band and valence band will be 100 eV and more done clear
  View Solution play_arrow

• question_answer89)
  Resistivity of a semiconductor depends on   [MP PMT 1999]
  A)
             Shape of semiconductor  done clear
  B)
             Atomic nature of semiconductor done clear
  C)
             Length of semiconductor        done clear
  D)
             Shape and atomic nature of semiconductor done clear
  View Solution play_arrow

• question_answer90)
  Electric current is due to drift of electrons in     [CPMT 1996]
  A)
             Metallic conductors done clear
  B)
             Semi-conductors done clear
  C)
             Both (a) and (b) done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer91)
  The energy gap of silicon is 1.14 eV. The maximum wavelength at which silicon will begin absorbing energy is [MP PMT 1993]
  A)
             10888 Å                                   done clear
  B)
             1088.8 Å done clear
  C)
             108.88 Å                                  done clear
  D)
             10.888 Å done clear
  View Solution play_arrow

• question_answer92)
  Which of the following energy band diagram shows the N-type semiconductor                                  [RPET 1986]
  A)
                                               done clear
  B)
                                      done clear
  C)
                                              done clear
  D)
                                           done clear
  View Solution play_arrow

• question_answer93)
  The mobility of free electron is greater than that of free holes because
  A)
             The carry negative charge done clear
  B)
             They are light done clear
  C)
             They mutually collide less       done clear
  D)
             They require low energy to continue their motion done clear
  View Solution play_arrow

• question_answer94)
  The relation between the number of free electrons in semiconductors (n) and its temperature (T) is
  A)
             \[n\propto {{T}^{2}}\]       done clear
  B)
             \[n\propto T\] done clear
  C)
             \[n\propto \sqrt{T}\]        done clear
  D)
             \[n\propto {{T}^{3/2}}\] done clear
  View Solution play_arrow

• question_answer95)
  The electron mobility in N-type germanium is 3900 cm2/v-s and its conductivity is 6.24 mho/cm, then impurity concentration will be if the effect of cotters is negligible
  A)
             1015 cm3                                  done clear
  B)
             1013 /cm3 done clear
  C)
             1012 /cm3                                done clear
  D)
             1016 /cm3 done clear
  View Solution play_arrow

• question_answer96)
  Which of the energy band diagrams shown in the figure corresponds to that of a semiconductor               [Orissa JEE 2003]
  A)
                                      done clear
  B)
  done clear
  C)
                                    done clear
  D)
  done clear
  View Solution play_arrow

• question_answer97)
  The energy band diagrams for three semiconductor samples of silicon are as shown. We can then assert that [Haryana CEE 1996]           
  A)
             Sample X is undoped while samples Y and Z have been doped with a third group and a fifth group impurity respectively done clear
  B)
             Sample X is undoped while both samples Y and Z have been doped with a fifth group impurity done clear
  C)
             Sample X has been doped with equal amounts of third and fifth group impurities while samples Y and Z are undoped done clear
  D)
             Sample X is undoped while samples Y and Z have been doped with a fifth group and a third group impurity respectively done clear
  View Solution play_arrow

• question_answer98)
  Carbon, silicon and Germanium atoms have four valence electrons each. Their valence and conduction band are separated by energy band gaps represented by (Eg)C. (Eg)Si and (Eg)Ge respectively. Which one of the following relationship is true in their case                                                  [CBSE PMT 2005]                
  A)
             \[{{({{E}_{g}})}_{C}}>{{({{E}_{g}})}_{Si}}\]                    done clear
  B)
             \[{{({{E}_{g}})}_{C}}={{({{E}_{g}})}_{Si}}\] done clear
  C)
             \[{{({{E}_{g}})}_{C}}<{{({{E}_{g}})}_{Ge}}\]                 done clear
  D)
             \[{{({{E}_{g}})}_{C}}<{{({{E}_{g}})}_{Si}}\] done clear
  View Solution play_arrow

• question_answer99)
  A semiconductor dopped with a donor impurity is  [AFMC 2005]    
  A)
             P-type                                     done clear
  B)
             N-type done clear
  C)
             NPN type                               done clear
  D)
             PNP type done clear
  View Solution play_arrow

• question_answer100)
  In a semiconducting material the mobilities of electrons and holes are me and mh respectively. Which of the following is true                                                                        [AIIMS 2005]
  A)
             \[{{\mu }_{e}}>{{\mu }_{h}}\]                                           done clear
  B)
             \[{{\mu }_{e}}<{{\mu }_{h}}\] done clear
  C)
             \[{{\mu }_{e}}={{\mu }_{h}}\]                                           done clear
  D)
             \[{{\mu }_{e}}<0;\ {{\mu }_{h}}>0\] done clear
  View Solution play_arrow

• question_answer101)
  Doping of intrinsic semiconductor is done    [Orissa JEE 2005]
  A)
             To neutralize charge carriers done clear
  B)
             To increase the concentration of majority charge carriers done clear
  C)
             To make it neutral before disposal done clear
  D)
             To carry out further purification done clear
  View Solution play_arrow