A two-dimensional electron gas (2DEG) forms at the interface of complex oxides like SrTiO3 (STO) and LaTiO3 (LTO), despite each material having a low native conductivity, as a band and a Mott insulator, respectively. The interface 2DEG hosts charge carriers with moderate charge carrier density and mobility that raised interest as a material system for applications like field-effect transistors or detectors. Of particular interest is the integration of these oxide systems in silicon technology. To this end we study the carrier dynamics in a STO/LTO/STO heterostructure epitaxially grown on Si(001) both experimentally and theoretically. Linear THz spectroscopy was performed to analyze the temperature dependent charge carrier density and mobility, which was found to be in the range of 1012cm2 and 1000 cm2V−1s−1, respectively. Pump-probe measurements revealed a very minor optical nonlinearity caused by hot carriers with a relaxation time of several 10 ps, even at low temperature. Density functional theory calculations with a Hubbard U term on ultrathin STO-capped LTO films on STO(001) show an effective mass of 0.64-0.68 me.
@article{arxiv.2503.21341,
title = {THz carrier dynamics in $SrTiO_{3}/LaTiO_{3}$ interface two-dimensional electron gases},
author = {Ahana Bhattacharya and Andri Darmawan and Jeong Woo Han and Frederik Steinkamp and Nicholas S. Bingham and Ryan J. Suess and Stephan Winnerl and Markus E. Grune and Eric N. Jin and Frederick J. Walker and Charles H. Ahn and Rossitza Pentcheva and Martin Mittendorff},
journal= {arXiv preprint arXiv:2503.21341},
year = {2025}
}