Abstract

The effect on the subband structure of the coupling between two coupled quantum wells is studied. An enhanced theoretical formalism based on the theory of Smith and Mailhiot¹ is used to model two GaAs quantum wells coupled through narrow Al_0.3Ga_0.7As barriers of widths between 11 and 17 angstroms. The wells are symmetric and vary in width between 11 and 100Å. Conduction, heavy and light hole subbands are calculated. It is found that the zone-center energy position of the subbands can be given by a simple function whose coefficients depend on the subband being considered. Also, the splitting between the symmetric and antisymmetric band pairs can be described using a simple function. The symmetric and antisymmetric subbands do not split evenly about the single well subband position as is sometimes assumed. The light hole 1 subband crossed the heavy hole 2 subband for narrow barrier and well widths. Additionally of interest, is the clear transition from a region where the subband positions are mainly given by quantum confinement effects to a region where material properties are more important. Comparison is made to experimental results and device applications are discussed.

© 1990 Optical Society of America