Impurity profiles of GaAs epitaxial layers doped with Sn, Si, and Ge grown with molecular beam epitaxy

Molecular beam epitaxy (MBE) n−type GaAs layers are commonly doped with Sn, Si, and Ge. The abrupt doping profiles resulting from these three dopants differed significantly when the epitaxy was carried out between temperatures ranging from 550 to 615 °C. The abrupt doped profile of Sn−doped GaAs layers when grown above 550 °C did not follow the time−intensity profile of the dopant beam, while layers doped with Si or Ge did. In the case of Sn, the effect is attributed to surface segregation during deposition.