Description of electron mobilities in epitaxial lanthanum-doped barium stannate films: Influences of LO phonons, threading dislocation, and ionized donor defects

Lanthanum-doped barium stannate (La-doped BaSnO3 or LBSO) has attracted the attention of researchers and engineers because of its wide range of potential applications in electronic and optoelectronic devices. This is due to a combination of its exceptional room temperature (RT) mobility of 320cm(2)V(-1)s(-1) and high visible range transparency. However, epitaxial LBSO films made using strategic deposition techniques such as molecular beam epitaxy, pulsed laser deposition, and magnetron sputtering show comparatively low RT mobilities, between 24 and 183cm(2)V(-1)s(-1), and an accurate description of these RT mobilities is still sought. Herein, we provide the underlying scattering mechanisms related to longitudinal optical (LO) phonons, threading dislocation, and ionized donor defects to elucidate the RT mobilities in LBSO epitaxial films. It was found that the total mobility estimated using Matthiessen's rule provided strong quantitative agreement with experimental results. The large polaron mobility based on LO phonon scattering dominated the whole spectrum of electron concentrations in this system. It was an upper bound mobility, i.e., the mobility limit attained at 320cm(2)V(-1)s(-1). The calculated mobility associated with LO phonon and threading dislocation scatterings adequately verified the experimental results between 150 and 183cm(2)V(-1)s(-1). The predicted results for all three scattering types were predominant in experimental data at less than 150cm(2)V(-1)s(-1). These investigations deepen our understanding of mechanisms governing the charge transport scattering in epitaxial LBSO films and pave the way for the development of novel semiconductor thin films for use in electronic and optoelectronic devices.