DOPING OF EPITAXIAL FILMS

• a possibility is autodoping: desorbtion of impurities from a film and incorporation in a another film
• another type of doping is doping during film growth:
  • Dopant sources: B₂H₆ - diborane, AsH₃ - arsine, PH₃ - phosphine (diluted with H₂)
  • The doping concentration depends on gas flow, temperature and deposition rate
  • For diluted flows, the incorporated dopant concentration C_dop ~ dopant gas flow
  • For hgh flows, the incorporated dopant concentration C_dop ~ (dopant gas flow)1/2
  • Lower temperatures allow higher doping
  • Dilution is required in order to obtain lightly doped layers
  • High doping (high dopant gas flow) slows the deposition rate by occupying sites
  • Segregation coefficient is defined as: , for K < 1 the dopant is rejected