Summary
X-ray diffraction techniques are used to investigate the strain compensation in GaAs: C/AlAs: C distributed Bragg reflectors (DBR) grown by solid-source molecular beam epitaxy. The strain compensation is achieved by introducing carbon doping up to densities of about 2×1020cm−3. The residual strain with respect to the GaAs substrate can be reduced to less than 1×10−4, which results in a large increase of the critical thickness of the DBR: C with regard to the undoped and Be-doped case. It is demonstrated that simulations of the X-ray diffraction rocking curves are essential to determine the chemical profile as well as the structural parameters of the GaAs: C and AlAs: C layers with high accuracy. The effective incorporation of carbon on lattice sites is deduced to be twice as large in AlAs: C than in GaAs: C for the same incident carbon flux. X-ray reciprocal space mapping reveals a structural degradation of the DBR: C for thicknesses above 2.5μm. The defect density is higher in GaAs: C than in AlAs: C.