Role of substrate strain to tune energy bands–Seebeck relationship in semiconductor heterostructures

In doped semiconductors and metals, the thermopower decreases with increasing carrier concentration, in agreement Pisarenko relation. Here, we demonstrate a new strain engineering approach to increase of [001] Si/Ge superlattices (SLs) beyond this Using two independent theoretical modeling approaches, show that bands form due structural symmetry, and, SL are highly tunable epitaxial substrate strain. The band shifts lead modulated thermopower, peak $\sim$5-fold enhancement strained SLs high doping regime.