MXene-GaAs heterojunctions: interface modeling, electronic properties and optical absorption

Abstract

MXene has gained favor in the field of material research and development due to its excellent two-dimensional structural properties, electronic structure properties, scalability, etc The heterostructures with MXene on one end not only make full use of the characteristics of MXene itself but also have the potential for transformative and application-rich materials when combined with other materials on the opposite end. Inspired by potentials in MXene-contained heterojunctions, this study focuses on the MXene-GaAs heterostructures to better understand their binding characters, structure features, and electron structures. First, the heterostructures (GaAs-Ti3C2O, GaAs-Ti3C2F, and GaAs-Ti3C2OH) are modeled aiming to provide comprehensive insights into their formation. The results reveal that the MXene layer in these heterostructures plays a crucial role in protecting the GaAs crystal, as evidenced by the substantial binding energy observed. Among the three heterostructures, GaAs-Ti3C2OH shows the closest proximity at the interface, attributed to the strong binding between MXene surfaces and Ga atoms. Various analyses, including binding energy calculations, charge polarization evaluations, interface electrostatic potential biases, and electron localization function studies, yield valuable insights into the formation process of these heterojunctions. Moreover, the incorporation of MXene layers enables electron conduction, effectively transforming the heterostructures into Schottky barriers. The density of states (DOS) analysis reveals pronounced peaks near the Fermi levels, indicating excellent electron mobility. Notably, all three heterostructures demonstrate weak magnetic features of the surface GaAs near the Fermi levels, imparted by the MXene layers. Lastly, optical simulations predict an absorption peak located around 4.3 eV for GaAs-Ti3C2OH.