Remote Phonon Scattering in Two-Dimensional InSe FETs with High-κ Gate Stack

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) materials like Indium Selenide (InSe) are promising for next-generation electronics.
• Electron mobility in 2D materials is crucial for device performance but is often limited by various scattering mechanisms.

Purpose of the Study:

• To investigate the impact of remote phonon scattering from substrates and high-κ gate dielectrics on electron mobility in 2D InSe field-effect transistors (FETs).
• To understand the temperature, inversion density, and thickness dependence of carrier mobility in InSe FETs.

Main Methods:

• Self-consistently solving Poisson and Schrödinger equations under quantum confinement using effective mass approximation.
• Calculating mobility via the Kubo-Greenwood formula, incorporating remote phonon scattering (RPS) and intrinsic phonon scatterings (acoustic, homopolar, optical, Fröhlich).
• Simulating InSe FETs with SiO₂, Al₂O₃, and HfO₂ dielectrics to analyze mobility degradation.

Main Results:

• Remote phonon scattering and Fröhlich interaction are major factors affecting electron transport in InSe.
• Mobility degradation is more severe with HfO₂ dielectric compared to Al₂O₃ and SiO₂.
• A SiO₂ interfacial layer effectively mitigates remote phonon scattering from high-κ dielectrics.
• InSe exhibits stronger mobility degradation with reduced layer number compared to MoS₂ due to smaller effective masses.

Conclusions:

• Remote phonon scattering is a critical factor limiting electron mobility in InSe FETs, influenced by the choice of gate dielectric.
• Strategic use of interfacial layers, like SiO₂, can enhance device performance by suppressing detrimental scattering mechanisms.
• The unique properties of InSe, including its effective masses, lead to distinct carrier density and layer number dependencies of mobility.