Characterization of linearly graded metamorphic InGaP buffer layers on GaAs using high-resolution X-ray diffraction

High-resolution X-ray diffraction (HRXRD) was used to characterize linearly graded metamorphic InGaP buffer layers grown at different temperatures on GaAs substrate by solid-source molecular beam epitaxy. The sample grown at 380 degreesC did not exhibit a Bragg diffraction peak corresponding to the top layers consisting of an InGaAs/InP single quantum-well structure, since it could not maintain a two-dimensional growth. When the samples were grow n at higher temperatures (430-480 degreesC), the top epitaxial layers were nearly fully relaxed and the strain relaxation anisotropy in two [110] dire ctions was found to be small. It was also found that the growth temperature of the buffer layer for these samples did not influence the strain relaxat ion ratio. Moreover, the full width at half maximum (FWHM) values of the XR D peaks suggest that the sample grown at 480 degreesC has better material q uality. (C) 2001 Elsevier Science B.V. Ah rights reserved.