DLTS and PR studies of partially relaxed InGaAs/GaAs heterostructures grown by MOVPE

摘要

The studies of electrical activity of deep electron traps and the optical response of partially-strain relaxed In_xGa_(1-x)As layers (x=5.5%, 7.7% and 8.6%) grown by metalorganic vapour-phase epitaxy (MOVPE) have been performed by means of deep-level transient spectroscopy (DLTS) and photoreflectance (PR). DLTS measurements revealed two electron traps. One of the trap has been attributed to electron states at a-type misfit dislocations. The other trap has been ascribed to the EL2 point defect. The PR spectra at room temperature were measured and analysed. By applying the results of theoretical calculations which include excitonic and strain effects, we were able to estimate the extent of strain relaxation and the values of residual strain in the partially relaxed epitaxial layers.