Differential Reflectance Studies of Structural Changes in GaAs Caused by Ar+ Ion Bombardment

Abstract

ABSTRACTDifferential reflection (DR) spectrometry has been used to investigate and characterize the effect of sputter damage of GaAs by Ar+ ions. The DR technique provides the photon-induced critical point interband transition energies which are sensitive to the electron and the crystal structure. The spectral dependence of the normalized difference in reflectivity is obtained by periodically scanning monochromatic light across a pair of GaAs samples. In the present case one part has been damaged by Ar+ ions with energies ranging from 500 to 5000 eV. The other half is the undamaged reference. The DR structure caused by interband transitions and designated as E1 and E1 + δ1 were found to shift in energy with increasing ion beam energy or with sputter damage. Two annealing stages were observed, one at 200°C and the other between 400°C and 450°C. They were attributed to different recovering mechanisms of As Frenkel pairs.