Flexoelectronic doping of the degenerate silicon and the correlated electron behavior

TL;DR

This paper demonstrates how strain-induced flexoelectric effects in metal/doped silicon bilayers can significantly alter electronic properties, inducing phenomena like Mott transition and magnetism, with potential applications in advanced electronics.

Contribution

It introduces the concept of flexoelectronic doping in silicon, revealing its impact on electron behavior and enabling control over material properties for quantum and spintronic devices.

Findings

Charge carrier concentration increases by two orders of magnitude.

Flexoelectronic polarization induces Mott transition and magnetism.

Potential for engineering electronic multiferroics.

Abstract

In metal/degenerately doped silicon bilayer structure, the interfacial flexoelectric effect due to strain gradient leads to charge carrier transfer from metal layer to the silicon layer. This excess charge carrier concentration is called flexoelectronic doping or flexoelectronic charge transfer, which gives rise to an electronically polarized (order of magnitude larger than ferroelectric materials) silicon layer. In the transport measurements, the charge carrier concentration in silicon is found to increase by two orders of magnitude due to flexoelectronic doping, which changes the Fermi level and the Hall response. The flexoelectronic charge accumulation modifies the electron-electron and the electron phonon coupling, which gives rise to Mott metal-insulator transition and magnetism of phonons, respectively. The coexistence of flexoelectronic polarization and magnetism gives rise to a new class of materials called electronic multiferroics. By controlling the flexoelectronic doping, material behavior can potentially be engineered for quantum, spintronics and electronics applications in semiconductor materials.