TAILORING INFRARED OPTICAL-PROPERTIES WITH SUPERLATTICES OF SUPERLATTICES

The concept of superlattices of superlattices (SOS's) is introduced to tailor infrared optical properties in semiconductor devices. SOS structures are constructed by alternating two different superlattices. By describing the separate superlattice sections in terms of their miniband edges and miniband-edge effective masses, and by using these parameters as input in a nested effective-mass theory, a transparent connection between the choice of material parameters and device properties is obtained. As one example of application we use the concept to propose SOS infrared detectors with more flexibility and potentially better performance compared to photodetectors based on conventional superlattices. In another example the idea is applied to lateral superlattices. It is shown that the desirable features of the SOS structures are robust against disorder in the layer thicknesses.