An investigation was made of the optical and structural properties, of tensile-strained GaxIn1-xP/InP heterojunctions, by means of cathodoluminescence scanning electron microscopy and transmission electron microscopy. The lattice mismatch of the samples ranged from 0.4% (x = 5.5%) to 0.84% (x = 11.8%). It was shown that, in agreement with previous studies, the relaxation of tensile-strained epilayers occurred via the emission of partial and perfect dislocations. The numerous twins and stacking faults which were found in the epilayers acted as efficient recombination centers for electron-hole pairs and appeared as dark-line defects in cathodoluminescence images. So-called ladder-like configurations of these defects were found, using transmission electron microscopic and cathodoluminescence techniques, in samples with a lattice mismatch of more than 0.5%. It was also demonstrated that dark-line defects were contaminated by impurities. Areas with networks of perfect dislocations were found between the dark-line defects. An analysis of the dislocation types suggested that the growth of low-mismatch samples was 2-dimensional, while it was 3-dimensional in highly-mismatched samples. The spatial variations of strain relaxation throughout the samples were studied by 77K cathodoluminescence spectroscopic measurements. It was shown that these variations could be correlated with the various types of structural defect.

F.Cléton, B.Sieber, A.Lefebvre, A.Bensaada, R.A.Masut, J.M.Bonard, J.D.Ganière, M.Ambri: Journal of Applied Physics, 1996, 80[2], 827-36