Phase transition of the Si(111)-4x1-In surface reconstruction investigated by electron transport measurements

TL;DR

This study investigates the temperature-dependent electron conductivity of the Si(111)-4x1-In surface reconstruction, revealing a metal-insulator phase transition at around 130 K and persistent surface Fermi level pinning.

Contribution

It provides the first direct transport measurement evidence of the phase transition in the surface states of Si(111)-4x1-In reconstruction.

Findings

Surface conductivity drops sharply at ~130 K indicating a phase transition.

Surface Fermi level remains pinned despite the phase transition.

Surface states retain free carriers down to low temperatures.

Abstract

We measure the electron conductivity of the surface states and the subsurface space charge layer originating from the Si(111)-4x1-In reconstruction as a function of temperature. The conductivity of the surface states drops sharply around 130 K with decreasing temperature, revealing a metal-insulator phase transition of the surface reconstruction. In contrast, the influence of the phase transition on the conductivity of the space charge layer is limited to temperatures above 60 K. This means that the surface Fermi level remains strongly pinned despite the phase transition, indicating the presence of free carriers in the surface states down to rather low temperatures.