Enhanced carrier densities in two-dimensional electron gas formed at BaSnO/SrTaOand SrSnO/SrTaOinterfaces.

Two-dimensional electron gases (2DEGs) realized at perovskite oxide interfaces offer great promise for high charge carrier concentrations and low-loss charge transport. BaSnO(BSO) and SrSnO(SSO) are well-known wide bandgap semiconductors for their high mobility due to the Sn--dominated conduction band minimum (CBM). Tawith a 5valence configuration in SrTaO(STaO) injects theelectron across the interface into the unoccupied Snstates in BSO and SSO. The present study uses ACBN0 density functional theory computations to explore charge transfer and 2DEG formation at BSO/STaO and SSO/STaO interfaces. The results of the ACBN0 computations confirm the Ta-to Sn-charge transfer. Moreover, the Sn--dominated CBM is located ∼1.4 eV below the Fermi level, corresponding to an excess electron density in BSO of ∼1.5 × 10cm, a ∼50% increase in electron density compared to the previously studied BSO/SrNbO(SNO) interface. Similarly, the SSO/STaO interface shows an improvement in interface electron density by ∼20% compared to the BSO/SNO interface. The improved carrier density in SSO/STaO and BSO/STaO is further supported by ∼13% and ∼15% increase in electrical conductivities compared to BSO/SNO. In summary, BSO/STaO and SSO/STaO interfaces provide novel material platforms for 2DEGs formation and ultra-low-loss electron transport.