Effects of the ion energy on damage production in MeV ion-implanted GaAs

The influence of the ion energy on damage production in GaAs was investigat ed by implanting Br ions with energies ranging from 0.6 to 9 MeV at room te mperature and 100 K. At room temperature the defect concentration in the ma ximum of the distributions decreases with increasing ion energy even if the nuclear deposited energy density is kept constant for ail energies. The be havior observed correlated with the nuclear energy deposited per ion and un it length which also decreases with the ion energy due to increasing range straggling. This increased range straggling for a given depth results in a reduction of the local current density and consequently in a more pronounce d in situ defect annealing. A reduction of the macroscopic ion current dens ity has a similar influence as the ion energy. At T-I = 100 K the damage pr oduction is neither influenced by the ion energy nor by the macroscopic cur rent density. The results obtained are discussed in the framework of the mo del of critical temperatures. (C) 2001 Elsevier Science B.V. All rights res erved.