INTERACTION OF A STRONGLY COUPLED SUPERLATTICE WITH TERMINATING QUANTUM-WELLS

Quantum wells are used to terminate the periodicity of a tightly coupl ed superlattice. When an electric field is applied, the quantum veils can interact with either the conduction or valence bands of the superl attice, depending upon the direction of the field, and whether the qua ntum wells are right-end or left-end terminations of the superlattice. We monitor the quantum-well-superlattice interactions with photocurre nt spectroscopy at 77 K. Quantitative analysis of the conduction- or v alence-band quantum-well-superlattice interactions depends sensitively on the band-offset ratio. The conduction-band and yalence-band offset s are determined separately and used to test the validity and utility of an empirical two-band effective-mass model for analysis of complex heterostructures with both thick (similar to 100 Angstrom) and thin (s imilar to 20 Angstrom) layers.