C-ENERGY-DEPENDENT RESIDUAL ION DAMAGE IN GAAS-C GROWN BY THE LOW-ENERGY ION-BEAM DOPING METHOD()

The effects of residual ion damage in low-energy (30 eV-30 keV) C+-dop ed GaAs investigated with regard to the electrical and optical activat ion of C as a function of C+ ion acceleration energy ECL. Systematic v ariation of E(C+) demonstrated that, in the energy range of E(C+) < 17 0 eV, the net hole concentration (\N-A-N-D\) slightly increases as E(C +) increase sand the highest \N-A-N-D\ was obtained al E(C+) = 170 eV under the constant C+ ion-beam current density. For E(C+) > 170 eV. an increase in E(C+) gave rise to an abrupt decrease of \N-A-N-D\ down t o two orders of magnitude smaller than that obtained al E(C+) 170 eV, Ln Low-temperature (2 K) photoluminescence spectra for as-grown sample s with E(C+) = 240 and 350 eV, a novel emission ascribable to residual ion damage was observed instead of an essential acceptor-acceptor emi ssion of [g-g](beta). However, subsequent annealing at 850 degrees C m ade this novel emission disappear and the proper [g-g](beta) emission was merely observed. An activation process observed for E(C+) = 5, 10, and 30 keV samples was very similar to that by high-energy ion implan tation, indicating low activation rate of 10%-15%. Minority-carrier li fetime measurements using scanning tunneling microscope stimulated lim e-resolved luminescence demonstrated the presence of residual ion dama ge in as-grown samples at E(C+) = 240 and 350 eV and annealed ones at E(C+) = 5, 10, and 30 keV while no ion damage was observed in as-grown sample at E(C+) = 30 eV, The incorporation and activation behaviors o f C atoms that take the Term of low-energy ions were found to be consi derably affected by changes in ion-surface interaction with increasing E(C+) and by the presence of residual ion damage in the layer. (C) 19 96 American Institute of Physics.