Page 77 - Principles of Catalyst Development
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64                                                       CHAPTER  4


                                 CONDUCTION  BAND  (EMPTY)



                                 Eg
                           ----- ------ - - - - -- -----::--- EF








                      Figure 4.14.  Electronic structure of an  intrinsic semiconductor.











                                  CONDUCTION  BAND
                           -------------------------------Eg
                         E  -------------------
                          F   -.  -.  -.  -.  -. DONOR  LEVELS






                                      n-type
                           anionic  vacancies,  interstitual  atoms


                                  CONDUCTION  BAND
                           -------------------------------Eg








                                      p-type
                         cationic  'Vacancies,  lower  valence  cations
                      Figure 4.15.  Electronic structure of impurity semiconductors.
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