In one direction, we attempt to “engineer” the density of states in order to have a peak near the Fermi energy. This idea was present by Mahan and Sofo more than a decade ago, PNAS 93, 7436 (1996). As an example of how we can impact this problem using quantum mechanical, atomistic calculations, on the left is a unit cell of ZnSe with oxygen substitutionally doped for selenium (corresponding to 3% oxygen on the left and 6% on the right). By varying the oxygen concentration and averaging over relative positions of the dopants, we can predict the impact on the DOS. We can do this for a range of materials as well as dopants, and our calculations have found that certain combinations create large features in the DOS near the Fermi energy. We’ve demonstrated this effect for both p-type and n-type materials.