Fig. 3
From: Double thermoelectric power factor of a 2D electron system
Experimental and theoretical analyses of the 2DES. a Cross-sectional HAADF-STEM image of the [1 uc SrTi0.4Nb0.6O3|11 uc SrTiO3]10 superlattice. Layer stacking sequence is also shown. Rather bright bands are seen near each SrTi0.4Nb0.6O3 layer. In the magnified image, the #4 atom in the B-site column is brighter than the nearby atoms, whereas no obvious difference is observed in the A-site column. EELS spectrum of #4 is broader than that of nearby atoms, indicating the coexistence of Ti4+/Ti3+ in the SrTi0.4Nb0.6O3 layers. b The calculated partial DOS of Nb 4d or Ti 3d in the [1 uc SrNbO3|10 uc SrTiO3] superlattice. The Fermi energy (EF) is located on the higher-energy side of the conduction band minimum for the first and second nearest neighbor (Ti first NN and Ti second NN). SrTiO3 layers together with 1 uc SrNbO3 layer (Nb) suggest that the electron carriers can seep from the SrTi1 − xNb x O3 layers into the SrTiO3 layers
