Native defects and substitutional impurities in two-dimensional monolayer InSe

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Indium Selenide (InSe) is a promising two-dimensional (2D) semiconductor with unique electronic properties.
• Developing novel 2D electronic devices requires understanding and controlling the n-type and p-type conductivities of InSe.
• Native defects and impurities significantly influence semiconductor properties.

Purpose of the Study:

• To investigate the properties of native defects and substitutional impurities in monolayer InSe.
• To determine the formation and ionization energies of these defects and impurities.
• To identify potential strategies for achieving n-type and p-type conductivity in InSe.

Main Methods:

• Employed first-principles calculations to study defect properties in monolayer InSe.
• Utilized an extrapolation approach to obtain convergent energies for charged defects in 2D materials, overcoming limitations of the traditional jellium scheme.
• Calculated formation energies and ionization energies for native defects (In and Se vacancies) and various substitutional impurities.

Main Results:

• Indium (In) vacancies were identified as deep acceptors, while Selenium (Se) vacancies are electrically neutral.
• Substitutional dopants at In or Se sites exhibited high ionization energies (0.41–0.84 eV).
• Halogen substitutions (X_Se, where X = Cl, Br, I) showed potential for n-type conductivity due to electron transport via defect-bound band edge states.

Conclusions:

• Native defects in InSe play a crucial role in its electrical conductivity.
• Achieving p-type conductivity might be feasible through In vacancies.
• Halogen doping presents a viable route for realizing n-type InSe for advanced 2D electronic applications.