Quantum-well anisotropic forbidden transitions induced by a common-atom interface potential

A prominent effect of the interface potential (IP) [E. L. Ivchenko and A. Y u. Kaminski, Phys. Rev. B 54, 5852 (1996); O. Krebs and P. Voisin, Phys. Re v. Lett. 77, 1829 (1996)], the optical anisotropy of the forbidden transiti ons in quantum wells has been observed by reflectance-difference spectrosco py. Predictions by the heavy-light-hole coupling IP models are qualitativel y consistent with all the observed features of the forbidden and the allowe d transitions. The fact that the predicted value of the relative, transitio n strength, which depends on neither the IP strength nor the electric field , disagrees with the observed one indicates that coupling involving X and/o r L bands may also be important. [S0163-1829(99)04227-7].