Abstract
Recently, the heterointerface between two band insulators, LaAlO3 and SrTiO3 has received much attention due to its high conducting behavior. The origin of conducting carriers at the LaAlO3/SrTiO3 heterointerface has been mainly explained by two distinct models: the polar catastrophe model and the atomic inter-diffusion model. The polar catastrophe model is based on a half electron transferred from polar LaAlO3 to nonpolar SrTiO3 to avoid the divergence of electric field without any atomic diffusions. The atomic inter-diffusion model is based on the transfer of dopants from LaAlO3 to SrTiO3 near the interface. However, the origin of the conducting carriers is still under debate and needs to be investigated further. In this study, we have examined the origin of conducting carriers at the LaAlO3/SrTiO3 heterointerface using the self-consistency calculations of Schrodinger equation and Poisson equation. We have studied the LaAlO3/SrTiO3 heterointerfaces with and without atomic diffusions. From the self-consistency calculations, carrier distributions, band structures, energy levels, and wavefunctions have been obtained. It has been found that the majority of electron is localized within a few nm from the interface forming two-dimensional electron gas, and multi-subbands are occupied indicating a multi-channel conducting behavior. We also calculated the electron mobility at the interface using the linearized Boltzmann equation including various scattering mechanisms, such as acoustic phonon, polar optical phonon, and remote charged layers in LaAlO3. The calculated mobility has been compared with available experimental data as a function of temperature and thickness of LaAlO3.