All- 3d Electron-Hole Bilayers in CrN/MgO (111) Multilayers for Thermoelectric Applications

CrN/MgO(111) multilayers modeled via ab initio calculations give rise to nanoscale, scalable, spatially separated two-dimensional electron and hole gases, each confined to its own CrN interface. Because of the Cr 3d3 configuration, both electron and hole gases are based on correlated transition-metal layers involving bands of 3d character. Transport calculations predict each subsystem will have a large thermopower, on the order of 250 μV/K at room temperature. These heterostructures combine a large thermoelectric efficiency with scalable nanoscale conducting sheets; for example, operating at a temperature difference of 50 K, 40 bilayers could produce a 1-V voltage with a film thickness of 100 nm.