Band alignment at InP/TiO₂interfaces from density-functional theory.

Area of Science:

• Materials Science
• Solid-State Physics
• Semiconductor Physics

Background:

• Understanding band alignment is crucial for designing heterojunctions in electronic and optoelectronic devices.
• Indium phosphide (InP) is a key semiconductor material, while titanium dioxide (TiO2) is a widely studied oxide with diverse polymorphs.

Purpose of the Study:

• To calculate the natural band alignments between InP and various TiO2 polymorphs (rutile, anatase, brookite, amorphous).
• To investigate the influence of interface structure on band alignment, particularly for amorphous TiO2 on InP.

Main Methods:

• First-principles calculations based on branch-point energies of InP and TiO2.
• Supercell calculations to model amorphous TiO2 grown on P-rich InP(001) surfaces.

Main Results:

• Type-I band alignment is predicted for all considered TiO2 polymorphs with InP.
• Microscopic interface structure significantly impacts band alignment; simulations show near-alignment of TiO2 conduction band with InP.
• Both type-I and type-II band alignments were observed depending on interface specifics.

Conclusions:

• The study highlights the critical role of interface structure in determining band alignment at InP/TiO2 heterojunctions.
• The findings align with recent experimental observations, validating the computational approach.
• This work provides valuable insights for the rational design of InP-based heterostructures.