STRUCTURAL ASPECTS OF HEAVILY CARBON-DOPED GAAS GROWN BY METALORGANIC MOLECULAR-BEAM EPITAXY (MOMBE)

X-ray diffraction analysis has clarified structural features of heavily carbon-doped GaAs films grown by metalorganic molecular beam epitaxy (MOMBE). X-ray quasi-forbidden reflection (XFR) intensity measurements have provided direct evidence that almost all the doped C atoms occupy As sites and cause large displacements of the nearest-neighbouring Ga and the second-nearest-neighbouring As atoms. X-ray rocking curve analysis has also shown that large lattice strain remains unrelaxed even for an epilayer far thicker than the critical thickness, although a high density of misfit dislocations has been observed by X-ray topography.