Relation between growth conditions and deep levels in GaAs grown by molecular‐beam epitaxy

Deep level transient spectroscopy (DLTS) has been studied in GaAs grown by molecular‐beam epitaxy. Samples were grown under As‐ or Ga‐stabilized conditions as well as in the transition region between the corresponding surface reconstructions. The layers exhibit different sets of DLTS peaks depending on the surface structure during growth. A minimum concentration, less than 1012 cm−3, was measured in samples grown in the transition region. The origin of the deep levels is related to the surface stoichiometry since the deep levels cannot be correlated either to the concentration of shallow levels or to chemical impurities detected by high‐sensitivity secondary ion mass spectroscopy.