Defects in weakly damaged ion-implanted GaAs and other III-V semiconductors

Under definite implantation conditions (small ion masses, sufficiently small ion fluences, and high implantation temperature) in III-V compounds weakly damaged layers are produced, which exhibit characteristic properties near the optical edge and an only slight increase of dechanneling of backscattered light ions. Especially for GaAs, InP, and GaP an exponential dependence of the near edge absorption coefficient on the photon energy according to K ∼ exp (h/2πω/E1) with E1 = 0.52 eV for GaAs, 0.33 eV for InP, and 0.6 eV for GaP is observed. From theoretical considerations it is concluded that this behaviour is connected with the existence of high concentrations of complexes containing antisite defects and vacancies. Combining optical measurements with TEM and measurements of the temperature dependence of the dechanneling gives further information about the structure of weakly damaged GaAs layers. The results of a complex analysis of weakly damaged GaAs and other III-V compound layers and first ideas about the damage structure in such layers are discussed. (author)