Applet Worksheet -- Indirect Recombination via a Deep Level

Answer the following questions based on the Introduction and Discussion and by referring to the applet.

1. In the applet, click in sequence: stop => select "electron trap" => start.

  1. Before capturing an electron, what are the possible charge states ?   Explain why !
       (1) +2    (2) +1    (3) 0    (4) -1   (5) -2
  2. After the electron capture, what are the possible charge states ?
       (1) +2    (2) +1    (3) 0    (4) -1   (5) -2
  3. The energy position Et in this applet is not appropriate.  Should Et be closer to Ec or should it be closer to Ev.  Why ?

2. stop => select "recombination" => start.

  1. From the order the carriers are captured in the applet (an electron first, followed by a hole), what conduction type is the semiconductor ?
      (1) n-type    (2) p-type
  2. Before capturing an electron, what charge state would the center be likely in ?  Why ?
       (1) +2    (2) +1    (3) 0    (4) -1   (5) -2
  3. After capturing an electron, what charge state would the center be likely in ?  Why ?
       (1) +2    (2) +1    (3) 0    (4) -1   (5) -2
  4. The energy Et is close to the midgap.  Is it appropriate for a recombination center ?

3. stop => selec "recombination2" => start.

  1. From the order the carriers are captured in the applet (a hole first, followed by an electron), what conduction type is the semiconductor ?
      (1) n-type    (2) p-type
  2. Before capturing an electron, what charge state would the center be likely in ?  Why ?
       (1) +2    (2) +1    (3) 0    (4) -1   (5) -2
  3. After capturing an electron, what charge state would the center be likely in ?  Why ?
       (1) +2    (2) +1    (3) 0    (4) -1   (5) -2

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Copyright (c)  1997-1998  Chu R. Wie, SUNY-Buffalo