Wannier-Stark localization of a strongly coupled asymmetric double-well GaAs/AlAs superlattice

A novel new type of superlattice (SL) structure which consists of strongly coupled asymmetric double-well (ADW) in one period have been investigated to introduce a new degree of freedom for the device functionality. The GaAs/AlAs ADW-SL contained in a p-i-n diode structure was grown by molecular beam epitaxy, and the electroabsorption properties were measured by low temperature photocurrent spectroscopy. It is found that the introduction of the confinement potential asymmetry with respect to electric field will lead to the selectivity of spatially indirect Stark-ladder transitions associated with two different types of the localized hole states, thus providing a new way of modulating the oscillator strengths. Assignment of the possible optical transitions from the miniband to the Stark-ladder regimes as a function of field strength is elucidated in detail by transfer matrix calculations.