Module 2 : Systems under technological importance

Lecture 12 : Inorganic semiconductors -Magnetic materials - 2

 

  • if impurity in crystal field has levels in the gap:
    deep levels (not hydrogenic), e.g., Te in GaAs
  • both shallow and deep levels can result from
    native defects: vacancies, interstitials…
  • if donors and acceptors are present: lower carrier
    concentration, compensation

 

 

 

Increasing doping:

hydrogenic impurity states overlap → form impurity band

For heavy doping the impurity band overlaps with the VB or CB