Graduated heterojunction in GaAs/AlAs quantum wells

Abstract
Molecular-beam epitaxy grown decoupled nominally square GaAs/AlAs multiquantum wells, producing levels deep in the well, have been studied by x-ray diffraction, photoluminescence excitation, and emission. The well width and period fluctuation (AlAs/GaAs/AlAs interface roughness) of the multiquantum wells were obtained by x-ray diffraction investigations. Using a smoothed profile of the interface as suggested by D. F. Nelson, R. C. Miller, C. W. Tu, and S. K. Sputz, Phys. Rev. B 36, 8063 (1987), the earlier verified theoretical approach [see Oelgart et al. Phys. Rev. B 49 (March 1994)] excellently predicts the experimentally observed transition energies.