High Mobile Two-Dimensional Electron Gas in LaAlO3/SrTiO3 Band-insulator Heterointerface
Jeong Ho You (Southern Methodist University), Shanshan Su (Southern Methodist University)
Synthesis, Characterization, and Modeling of Low-Dimensional Nanomaterials
Wed 10:45 - 12:15
Salomon 202
Heterostructures consisting of two perovskite band insulators, LaAlO3 (LAO) and SrTiO3 (STO) have received much attention due to the presence of high mobile two-dimensional electron gas (2DEG) at the interface. In this study, electron transport properties at n-type LAO/STO interfaces have been investigated numerically. Carrier distributions, band structures and electron sheet density have been calculated by solving Schrödinger equations with Poisson equation in a self-consistent manner for various LAO/STO interfaces, including the A-site, B-site and AB-site atom interdiffused interfaces and the sharp interface (i.e., no interdiffusions). It has been found that the interface with A-site atom interdiffusion has the critical thickness of 4 unit cells below which it remains insulating. The other interfaces have the critical thickness above 4 unit cells. For the A-site interdiffused interface, most electrons are localized within 10 nm from the interface forming 2DEG with multi-band occupations. Along the A-site atom interdiffused interface the electron mobility has been calculated using the linearized Boltzmann transport equation including scattering mechanisms of acoustic phonon, polar optical phonon, interface roughness and net charged layers. The calculated mobility is compared with available experimental data. At low temperature, the mobility is limited by the interface roughness and net charged layers. At room temperature, the polar optical phonon is the dominant electron scattering mechanism and the mobility is almost independent from the thickness of LaAlO3 film.