Enhanced carrier densities in two-dimensional electron gas formed at BaSnO 3 /SrTaO 3 and SrSnO 3 /SrTaO 3 interfaces.

Two-dimensional electron gases (2DEGs) realized at perovskite oxide interfaces offer great promise for high charge carrier concentrations and low-loss charge transport. BaSnO 3 (BSO) and SrSnO 3 (SSO) are well-known wide bandgap semiconductors for their high mobility due to the Sn- 5s -dominated conduction band minimum (CBM). Ta 4+ with a 5 d 1 valence configuration in SrTaO 3 (STaO) injects the d 1 electron across the interface into the unoccupied Sn -5s states 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- 5d to Sn- 5s charge transfer. Moreover, the Sn- 5s -dominated CBM is located ∼1.4 eV below the Fermi level, corresponding to an excess electron density in BSO of ∼1.5 × 10 21 cm -3 , a ∼50% increase in electron density compared to the previously studied BSO/SrNbO 3 (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.