Undoped AlAs/GaAs distributed Bragg reflectors with a density of misfit dislocations close to zero were obtained. The reduction in misfit dislocation density was achieved by increasing the temperature distribution homogeneity in the growing crystal by using a higher wafer rotation rate. Two structures of distributed Bragg reflectors were crystallized using molecular beam epitaxy under the same optimal growth conditions. The growth runs differed only in the rotation rate of the wafers. X-ray topography revealed no residual misfit dislocations in the case of faster rotation. The distributed Bragg reflector structure with residual misfit dislocation density was still highly strained. No additional relaxation process occurred; as confirmed by the angular position of the distributed Bragg reflector zeroth-order peak in high-resolution X-ray diffractometry rocking curves.

The Reduction of the Misfit Dislocation in Non-Doped AlAs/GaAs DBRs. A.Jasik, W.Wierzchowski, J.Muszalski, J.Gaca, M.Wójcik, K.Pierściński: Journal of Crystal Growth, 2009, 311[16], 3975-7