Electronic correlation effects and Coulomb gap in the Si(111)-$(\sqrt{3}\times\sqrt{3})$-Sn surface

TL;DR

This study investigates the electronic transport and Coulomb gap in the Si(111)-$(\sqrt{3} imes\sqrt{3})$-Sn surface, revealing a Mott-Hubbard insulating ground state with temperature-dependent conductivity and Coulomb blockade effects.

Contribution

It provides new experimental evidence of the Coulomb gap and insulating behavior in the Si(111)-$(\sqrt{3} imes\sqrt{3})$-Sn surface, combining tunnelling spectroscopy and conductivity measurements.

Findings

Ground state is a Mott-Hubbard insulator with a 70 meV gap.

Surface conductivity follows Efros-Shklovskii hopping law above 50K.

Localization length of electrons is approximately 7 Å.

Abstract

Electronic transport properties of the Si(111)-$(\sqrt{3}\times\sqrt{3})$-Sn surface formed on low doped Si substrates are studied using two-probe conductivity measurements and tunnelling spectroscopy. We demonstrate that the ground state corresponds to Mott-Hubbard insulator with a band gap $2\Delta = 70$meV, which vanishes quickly upon temperature increase. The temperature dependence of the surface conductivity above $T > 50$K corresponds to the Efros-Shklovskii hopping conduction law. The energy gap at the Fermi level observed in tunnelling spectroscopy measurements at higher temperatures could be described in terms of dynamic Coulomb blockade approximation. The obtained localization length of electron is $\xi = 7$\AA.