DAMAGE PRODUCTION IN GAAS DURING MEV ION-IMPLANTATION

The influence of the nuclear and electronic energy loss on the damage production in GaAs has been studied by Se+ ion implantation al T-l = 2 93 K with energies ranging from 2 MeV up to 20 MeV, The ion dose was v aried between 5 x 10(12)/cm(2) and 1 x 10(15)/cm(2). The damage produc tion was investigated using RES in channeling regime, Temperature and energy dependent backscattering measurements and TEM investigations we re performed to study the kind of defects in more detail. The resultin g defect profiles are compared with the depth distribution of the nucl ear and electronic energy loss which were simulated by TRIM 87. The re sults show that the remaining defect concentration strongly decreases with increasing implantation energy even if the same energy density is deposited into nuclear processes, We suppose, that the electronic ene rgy loss increases the defect transformation and annealing during impl antation at T,= 293 K, The defects in the samples implanted with energ ies greater than 5 MeV are characterized as point defects, point defec t clusters and small dislocation loops; the kind of defects are the sa me over the whole implantation depth and the existence of amorphous zo nes can be widely excluded.