Mechanism of Fermi Level Pinning at Metal/Germanium Interfaces

TL;DR

This study investigates the physical mechanisms behind Fermi level pinning at metal/germanium interfaces using atomically matched heterostructures, revealing rectifying behavior and Schottky barriers that distinguish intrinsic from extrinsic effects.

Contribution

It provides new insights into Fermi level pinning by analyzing atomically matched Fe3Si/Ge interfaces and demonstrating rectifying behavior unlike conventional junctions.

Findings

Observation of rectifying I-V characteristics in Fe3Si/Ge junctions

Measurable Schottky barrier height depending on contact area

Distinction between intrinsic and extrinsic mechanisms for Schottky barrier formation

Abstract

The physical origin of Fermi level pinning (FLP) at metal/Ge interfaces has been argued over a long period. Using the Fe$_{3}$Si/Ge(111) heterostructure developed originally, we can explore electrical transport properties through atomically matched metal/Ge junctions. Unlike the conventional metal/$p$-Ge junctions reported so far, we clearly observe rectifying current-voltage characteristics with a measurable Schottky barrier height, depending on the contact area of the Fe$_{3}$Si/Ge(111) junction. These results indicate that one should distinguish between intrinsic and extrinsic mechanisms for discussing the formation of the Schottky barrier at metal/Ge interfaces. This study will be developed for understanding FLP for almost all the metal/semiconductor interfaces.