The lattice relaxation that was produced by the metastable configuration of EL2-like defects in layers that had been grown by means of molecular-beam epitaxy at about 200C were studied by using high-resolution X-ray diffraction. Illumination with 900 to 1100nm light at 77K caused a broadening of the diffraction peak and a shift towards higher Bragg angles (decreased lattice constant). An analysis of step-etched samples, as well as reciprocal lattice mapping, indicated that the peak broadening was caused mainly by a variation in the lattice constant, parallel to the surface. Recovery of the peak was observed after prolonged illumination with 1350nm light or after increasing the temperature to about 130K.

M.Leszczynski: Physical Review B, 1996, 53[16], 10699-702