TRICLINIC DEFORMATION AND ANISOTROPIC STRAIN RELAXATION OF AN INAS FILM ON A GAAS(001) SUBSTRATE MEASURED BY A SERIES OF SYMMETRICAL DOUBLE-CRYSTAL X-RAY-DIFFRACTION

We presented a series of symmetric double crystal X-ray diffraction (D CXD) measurements, (0 0 4), (2 2 0) and (2 - 2 0) diffraction, to inve stigate the strain relaxation in an InAs film grown on a GaAs(0 0 1) s ubstrate. The strain tensor and rotation tensor were calculated accord ing to the DCXD results. It is found that the misfit strain is relaxed nearly completely and the strain relaxation caused a triclinic deform ation in the epilayer. The lattice parameter along the [1 1 0] directi on is a little longer than that along the [1 - 1 0] direction. Further more, a significant tilt, 0.2 degrees, towards the [1 1 0] direction w hile a very slight one: 0.002 degrees, towards [1 - 1 0] direction wer e discussed. This anisotropic strain relaxation is attributed to the a symmetric distribution of misfit dislocations, which is also indicated by the variation of the full-width at half-maximum (FWHM) of (0 0 4) diffraction along four azimuth angles. (C) 1998 Elsevier Science B.V. All rights reserved.