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semiconductormore about semiconductor

semiconductor

 

  2  definitions  found 
 
  From  WordNet  r  1.6  [wn]: 
 
  semiconductor 
  n  1:  a  substance  as  germanium  or  silicon  whose  electrical 
  conductivity  is  intermediate  between  that  of  a  metal  and 
  an  insulator;  it  increases  with  temperature  and  in  the 
  presence  of  impurities 
  2:  a  device  made  with  semiconducting  material  [syn:  {semiconductor 
  device},  {semiconductor  unit}] 
 
  From  The  Free  On-line  Dictionary  of  Computing  (13  Mar  01)  [foldoc]: 
 
  semiconductor 
 
    A  material,  typically  crystaline,  which  allows 
  {current}  to  flow  under  certain  circumstances.  Common 
  semiconductors  are  silicon,  germanium,  gallium  arsenide. 
  Semiconductors  are  used  to  make  {diodes},  {transistors}  and 
  other  basic  "solid  state"  electronic  components. 
 
  As  crystals  of  these  materials  are  grown,  they  are  doped" 
  with  traces  of  other  elements  called  {donors}  or  {acceptors} 
  to  make  regions  which  are  n-  or  p-type  respectively  for  the 
  {electron  model}  or  p-  or  n-type  under  the  {hole  model}. 
  Where  n  and  p  type  regions  adjoin,  a  junction  is  formed  which 
  will  pass  {current}  in  one  direction  (from  p  to  n)  but  not  the 
  other  giving  a  {diode}. 
 
  One  {model}  of  semiconductor  behaviour  describes  the  doping 
  elements  as  having  either  {free  electrons}  or  {holes}  dangling 
  at  the  points  in  the  crystal  lattice  where  the  doping  elements 
  replace  one  of  the  atoms  of  the  foundation  material.  When 
  external  electrons  are  applied  to  n-type  material  (which 
  already  has  free  electrons  present)  the  repulsive  force  of 
  like  charges  causes  the  free  electrons  to  migrate  toward  the 
  junction,  where  they  are  attracted  to  the  holes  in  the  p-type 
  material.  Thus  the  junction  conducts  current. 
 
  In  contrast,  when  external  electrons  are  applied  to  p-type 
  material,  the  attraction  of  unlike  charges  causes  the  holes  to 
  migrate  away  from  the  junction  and  toward  the  source  of 
  external  electrons.  The  junction  thus  becomes  depleted"  of 
  its  charge  carriers  and  is  non-conducting. 
 
  (1995-10-04)




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