Superlattice structures for thermoelectric devices

A thin-film structure comprising:

• a plurality of superlattice periods, each superlattice period comprising a first material layer disposed adjacent to a second material layer;
• wherein the plurality of superlattice periods comprises:
• a first superlattice period wherein a thickness of a first material layer of the first superlattice period is x and a thickness of a second material layer of the first superlattice period is 3x;
• a second superlattice period disposed adjacent the first superlattice period, wherein a thickness of a first material layer of the second superlattice period is x and a thickness of a second material layer of the second superlattice period is 4x;
• a third superlattice period disposed adjacent the second superlattice period, wherein a thickness of a first material layer of the third superlattice period is x and a thickness of a second material layer of the third superlattice period is 5x;
• a fourth superlattice period disposed adjacent the third superlattice period, wherein a thickness of a first material layer of the fourth superlattice period is x and a thickness of a second material layer of the fourth superlattice period is 6x;
• and
• a fifth superlattice period disposed adjacent the fourth superlattice period, wherein a thickness of a first material layer of the fifth superlattice period is x and a thickness of a second material layer of the fifth superlattice period is 7x.