Band offsets at semiconductor-oxide interfaces from hybrid density-functional calculations

Area of Science:

• Materials Science
• Computational Chemistry
• Solid-State Physics

Background:

• Accurate determination of band offsets at semiconductor-oxide interfaces is crucial for designing advanced electronic and optoelectronic devices.
• Existing methods often struggle with precision, necessitating improved theoretical approaches.

Purpose of the Study:

• To develop and validate a robust computational scheme for predicting band offsets at semiconductor-oxide interfaces.
• To assess the accuracy of the proposed method against experimental data for key material systems.

Main Methods:

• Utilized hybrid density functionals incorporating a fraction (alpha) of Hartree-Fock exchange.
• Tuned the fraction alpha for each bulk material to reproduce experimental band gaps.
• Determined band edge positions relative to a reference level using interface calculations.

Main Results:

• The proposed scheme accurately predicts band offsets for Si-SiO2, SiC-SiO2, and Si-HfO2 interfaces.
• The alignment of bulk reference levels proved largely independent of the fraction alpha.
• Achieved excellent agreement between calculated and experimental band offset values.

Conclusions:

• The developed hybrid density functional scheme provides a reliable method for calculating semiconductor-oxide band offsets.
• This approach offers high accuracy and is applicable to various technologically relevant interfaces.
• The findings contribute to the fundamental understanding and predictive modeling of heterojunction properties.