Transport properties of the n-type SrTiO3/LaAlO3 interface

The thermoelectric properties of the (001) n-type 6.5STO/1.5LAO interface were investigated by means of the all-electron full-potential method based on the semi-classical Boltzmann theory. Calculations show that the n-type 6.5STO/1.5LAO interface exhibits non-zero density of states at the Fermi level (E-F), which leads to unusual transport properties and enhances the electrical conductivity. The influence of the temperature on the carrier mobility and the carrier concentration has been investigated. The calculated carrier concentration as a function of temperature is in concordance with previous experimental and theoretical work. At above the E-F, a significant increase in the electrical conductivity occurs to reach the maximum value 1.98 x 10(20) (Omega m s)(-1) at mu - E-F = 0.05 eV for 300 K, confirming that the 6.5STO/1.5LAO interface is an n-type conduction. The Seebeck coefficient has a negative sign, which confirms that the 6.5STO/1.5LAO interface is an n-type conduction in the vicinity of EF. It has been found that the power factor is zero at low temperature, which rapidly increases to reach its maximum value 8.1 x 10(11) W m(-1) K-2 s(-1) at 900 K. Furthermore, the transport coefficients were investigated as a function of chemical potential at three constant temperatures (300, 600 and 900 K). We would like to highlight that our calculated Seebeck coefficient and carrier concentration are in concordance with previous experimental and theoretical work on 4, 5 and 6 u.c. STO/LAO interfaces. The large Seebeck coefficient is attributed to the non-zero density of states at the E-F. The increase of the Seebeck coefficient also leads to a maximum of the power factor.